U.S. Army/Military's response time to an army appearing in the middle of a major city

Question

In the scenario I have in mind, a handful of portals appear in a major U.S. city from which an army of golems starts pouring forth with the intent to cause as much damage as possible.

The specifics of this magical army aren't very important—assume they are dangerous enough to warrant a military response.

And for the sake of the argument, let's say the city in question is Los Angeles.

How long would it take for the army/national guard/military (or whatever) to mobilize and start dealing with this sudden invasion?

Edit: For those curious as to how effective modern weaponry would be against the army of golems:

The Golem's don't feel pain nor fear, and thus wouldn't hesitate to walk into a hail of bullets or charge at tanks.

Small arms fire would indeed be almost completely ineffective. Powerful/Heavy enough Tanks (?) would be capabable of crushing Golems underfoot but it would be more akin to crushing rocks than squishy human bodies.

Although they posses a great deal of strength, they lack ranged options.

I won't specify their numbers, however, but I will say that they aren't endless. The military would win against them in the end.

Armed Citizen response is expected, but not really the point of the question.

Answer 1

It wouldn't be an 'all at once' kind of scenario. It would probably go down something like this:

0-1 hours: Initial invasion. Massive wave of 911 calls results in large scale but uncoordinated response by local police.

1-2 hours: Scale of event begins to become apparent. SWAT teams are deployed, but not in a very coordinated way. State Governor calls up the National Guard. Active Duty Guard are ordered to report to their armories.

2-4 hours: First wave of organized response from National Guard units with the Active Duty Guardsmen who were in close proximity to their armories. Reserve Guard units are called to report in. State Governor declares a state of Emergency and requests aid from the Federal government.

4-8 hours: Second wave of organized response from National Guard units. All Active Guard should be mobilized at this point. Reserve Guard are in the process of reporting in. Initial response from US Armed Forces depending primarily on proximity of bases. Continuous presence of Air National Guard and USAF aircraft above the city. Possibly Navy and Marines as well depending on the city. National Guard armored vehicles will be in the streets, Army and Marine as well again depending on base proximity.

8-24 hours: Increasing level of response from National Guard and US Armed Forces as units from further away are recalled to duty and deployed. By the end of 24 hours all local Guard should be mobilized and responding, and Guard units from neighboring states will be arriving. Massive and continuous response by USAF, USN, and USMC aircraft, especially in any coastal city.

Answer 2

The answers discussing USA response are very good (time to get armor from Hood, etc.)

But I would add that air attack would be very effective (big bombs blow rocky golems apart, heavier canons for golem breaking) and unopposed (lack of golem ranging weapons). Within the day many, many Naval and Air Force aircraft in the Western US and offshore could respond. It wouldn't even be much issue at all to do the bombs load. Aircraft carriers are ready for this sort of thing and full of bombs. I don't think the Chair Force would take long either.

In addition, there are significant armor assets at Camp Pendleton that are USMC and about an hour south on I-5 (with no traffic, haha).

P.s. I have personally launched Tomahawks (for exercises) from sea that landed onshore in SOCAL. While it would not make sense to use these weapons against moving golems, you could certainly take out the portel(s) as soon as targeting was available and orders dispatched. Within a day for sure.

P.s.s. I know you are just trying to gather information to help you, but this plan is a no-go. Perhaps if you asked the board, how to prevail with your golem attacks? (Maybe drop them into our command and control areas? But I don't want to help you too much.)

Answer 3

Lightly-armed troops would arrive in a few hours. Useful amounts of heavy armor and weaponry would take days.

This answer ignores USAF and USMC fighting response, since the OP asked specifically for Army. (looks like an edit changed that)

Getting troops there isn't the problem.

The nearest National Guard brigade is at San Diego, with subordinate battalions much closer to Los Angeles. Those troops are, of course, mostly at their homes and civilian schools and jobs. Mustering most would be a matter of a few hours.

The nearest Regular Army brigade is usually at Fort Irwin, CA, going through a rotation at the National Training Center. The troops would need to be pulled out of the field, refueled and resupplied, and reoriented to the new mission. Most of that brigade can be in Los Angeles within 12 hours...but only lightly armed.

More troops can fly in from Ft Hood and Ft Stewart within a day. The entire 40th Infantry Division (CAARNG) would be there within two days...but only lightly armed.

The REAL problem is getting enough ammunition to those troops.

Fighting units within the USA do NOT keep large stocks of ammunition for heavy weapons (javelins, tank rounds, artillery, etc) on-hand. That would be unwise and risky for many reasons. Instead, most units have a small supply of light ammunition for force protection on-hand, and depend upon the Army to send most ammunition to forward resupply points for pickup. Minor stocks are nearby at pickup points like Ft Irwin and Camp Roberts.

The closest large number of tank units are away in Texas. They would take days to arrive by rail or truck. While the tanks of the local 18th Armored Cavalry Regiment would do what they can, the question implies greater numbers than a single valiant squadron can perhaps conveniently handle...especially with rapidly dwindling ammunition.

The closest major stocks of ammunition are away in Utah and Oklahoma. It will take at least a day to marshall the aircraft to begin airlifing ammunition to California. Each flight of ammo is one less flight of soldiers or equipment. Even with airlift, expect depot-to-tank-crew delivery time to be about 2-3 days. The airlift must last about 5-6 days, then the first ammo trains and convoys begin to arrive. Distribution under the best of circumstances takes 1-2 days...and these won't be the best of circumstances.

Answer 4

These days all Western countries are alert to the danger of a Mumbai-style terrorist attack, involving a significant number of gunmen with automatic weapons attacking a crowded city location. It is reasonable to assume that LA is well-organised and briefed do deal with this. (In the UK, an SAS unit helicoptered in within minutes of a terrorist attack in London). Expect a rapid-response force from co-ordinated government agencies to arrive very quickly while local police attempted to cordon off the area.

What happens next depends a lot on the level of intelligence they can obtain and the politics -- using US forces in the US is a bit of an issue. The big problem is that nobody is going to believe an alien invasion straight off, which will cause delays while the drones from border security are re-tasked with collecting data on the invasion force.

A quick Google suggests there are no significant Army/USMC bases with suitable armor close to LA. A mobile reaction force (light armor) could be flown in less than 12 hours from approval, the heavy stuff will take days. I suspects the Corps of Engineers will be your most effective tool.

Speaking of which, from the description, Army equipment may not be what's needed. A construction firm with lots of bulldozers, wrecking balls and earthmoving plant, with military reserve staff at the wheel, might prove way more effective than guys with M-4s and rocket launchers. Especially if they have plenty of demolition charges and someone adept at martial-arts use of a jackhammer. Hell, even a quickly-excavated trench might be enough to stop the golems - then just fill it in with liquid cement.

I'd also like to explore the possibility of dropping improvised barrel-bombs from civilian helicopters -- plenty of those to commandeer in LA! And you'd get the whole thing filmed at the same time for the movie...

Answer 5

For quick response, armed attack helicopters and / or jets.

There are three weapons that armed attack helicopters provide for use against golems; some of the comments up stream imply that small arms may or may not be effective. (This answer, mildly informed by some QRF operations I was involved with IRL, is aimed at helping you tell your story)

1. Hellfire Missiles. They can have HE or anti armor head. (I'd go HE for flesh golems)
2. 2.75 inch rockets(Hydra). In 2011, the effort to upgrade those to include a seaker head that followed laser designation was successful; APKWS. They are now in the inventory (in various flavors).
3. 20mm or 30mm multi barreled machine gun. (Cobra or Apache)

Depending on the readiness level of the base in question, be it an Army National Guard base, an active Army base, or a Marine Corps base (like Camp Pendelton between LA and San Diego) the briefing, arming and transit time would be between 2-4 hours if the call for support comes during the day. If it's in the middle of the night or at 2:00 AM, a bit longer. That time span is subject to your authorial intent and desire. If someone says "US is under attack, I need ... X" the need for rapid response is understood at a place like Camp Pendelton (or similar military base).

Some useful jets: A-10s, F-16s, F-15Es, F-35s.

You could expect a response from Nellis Air Force Base in Nevada to arrive in about the same time if you (1) posited an alert state that got them armed quickly, and / or (2) if the units flying those aircraft were in a live fire exercise.

More useful Jets: F-18 (E/F) and / or F-35

From Fallon Nevada (Strike U), or from NAS Lemoore, you could posit a similar armed alert that, once someone called and said "Golems attacking, need armed jets over LA as soon as you can." With sufficient motivation and command requirement, 2-4 hours to get armed, briefed, and launched. MCAS Miramar likewise with armed air assets, as they have recently received F-35Cs.

In the time that it takes to get them briefed, armed, and enroute, in parallel (time-wise) someone local (National GUard or Air National Guard personnel) who is a FAC or a JFAC (Forward Air Controller) would need to be moving to be near the scene to get "eyes on target" for the air units. There are airborne FACs qualified in Marine squadrons. (I can't remember how USAF does airborne FAC at the moment) You could have an airborne FAC from Pendelton fullfil that role in your story.

All of the above aircraft have precision weapons: laser designated bombs and missiles. The 20mm and 30mm cannons are quite accurate, but the risk of collateral damage goes up a bit.

Air Assault in support

While all of that is going on, you can get some platoon strength Marine or Army units from the nearby bases armed with grenade launchers, .50 cal (Ma Deuce), and with anti-tank weapons. (Something like the AT-4). CH-53E or Osprey(V-22) can get them to the fight and arrive a little while after the attack helicopters go in. The problem there is to scramble a few platoons of appropriately armed infantry (heavy weapons platoon or Antitank platoon), get them to the airfield, get them briefed and armed (can be done in parallel) and then off they go. Air Assault is a thing that both the Army and Marines practice a lot.
That initial ground force will need to be reinforced rapidly. The transport aircraft can refuel at Pendelton/Army Base/etc (the USMC can hot-refuel with rotors turning) when they come to reload with the next platoon/company that got assembled, briefed and armed up. The size of the "Army" of golems informs just how dire the tactical situation is and how large of a response is needed. Battalion level? Brigage/Regiment level? Division? Corps? A Joint Task force HQ would probably fall in on the initial response/QRF force within 24-48 hours.

It takes time, but you can speed it up a little for narrative effect.

Heavier units; probably a day or so more before they can get to the fight.

If you want Bradleys / Strikers / Tanks, other Armored Fighting Vehicles, that will take a bit more time. The police have a collasal task of clearing the highways into LA from all of the people who are fleeing LA to allow the Army/Marines to roll in the heavy armor. I'd not have them arrive until the following day. And if you want to get your stubby pencil out, you can also force the issue of someone setting up FARPS (Feuling and arming points) so that the tanks and helicopters can stay in the fight ... not sure how many golems you have rolling in, and how long you envision the fight going on for.

Answer 6

I would think you'd want to chose the portal location based on how effective/fast you want the response to be. And there are further dials beyond that.

LA

LA is just north of "Marine Corps Base Camp Pendleton", HumV's galore, LCACs (hovercraft that can take a tank, a few HumVs, or a crap load of soldiers), tanks, artillery, probably some attack helicopters). It's not much further north from "Marine Corps Air Station Miramar". They will have plenty of close air support available.

You can edit the response time if you like given an officer willing to "ask for forgiveness rather than permission". Given some company of anti armor light vehicles on a live fire training mission in the big swath of desert between LA and SD, you could have 50. cal HMGs, full auto 40mm grenade launchers, and anti-tank missiles on scene in under an hour.

Want to motivate that officer to react faster than is prudent for ones career? Say their family lives off base near one of the portals. Make that officer the kind of awesome sauce who's soldiers would literally follow him (or her?) into hell... and you've got military weaponry on scene in under an hour.

You could even suppose this officer is good friends with a local police chief (they served together of course) and "I saved your goddam life and I'm calling that favor due!" Instant police escort, just add cell phone.

And if you want to pull out the REALLY big guns, there's also Naval Base San Diego. I don't think anyone will want to drop a 16-inch shell in LA, but you could rationalize it.

I'm thinking the 20mm cannon on super cobras' chin turret could really wreck your golems without fear of reprisal and relatively little collateral damage... could probably go straight through their center of mass, and blast the leg off the golem behind the first one, but then the round just blows a hole in the street/lawn. The sewer system might take some damage, but it's not like you're putting ever round through several houses like you might with an M2 50 cal from a hummer.

Other

I suggest you find a map of military bases, and compare that with all cities over some size (1 million people perhaps), and pick something relatively isolated, or even more well covered, depending on your needs.

You might also want to consider guns per capita, and what kind of guns they might be. I'd expect far more people in Alaska to have ready access to something heavy (to deal with bears and moose (and skverl!), and therefor more likely to drop your golems in a hurry) rather than the kinds of firearms you'd find somewhere like New York were the guns/capita is relatively low, and you only have to worry about other people.

Answer 7

In 2004 there was a man named Marvin Heemeyer, due to his belief that the government was unfairly destroying his livelyhood he armored up a bulldozer and had a night on the town. It lasted around 2 hours before he got stuck in a basement.

From what I recall the authorities were going to call in the guard to dispose of him, but they figured it'd do more damage and then he took care of himself by getting stuck in the basement.

From that you can probably get at least two hours of decision making before the guard is called.

As a bonus, since your town undoubtedly has a road department with backhoes, bobcats and dozers; which means they should be able to defend themselves a little bit.

Heck since these monsters are weak enough that small arms will eventually crack 'em, car accidents would cripple them. Just have Billy Bob put his f150 into reverse and hit the gas. His truck'll be toast but so will the invader.

If this was in a state with harsh winters we could even have a charge of the snowplow brigage!