So, looking at the situation, yes, this is a scenario where Earth comes under attack. I will start to copy-paste and update the lore as I write this question.....now:
The Gdarje (the name of the extraterrestrials) initially began to investigate Earth with probes and research vessels as early as WWI (in real life, this is untrue), but in 1961 (the first PoD), an extraterrestrial research vessel is shot down by US F-4 Phantom IIs and Guatemalan P-51s, (the latter being completely wiped out by infrared lasers), initially thinking it was a Soviet experimental spy plane (an assumption taken from its starting trajectory above Cuba), and then a joint operation between US Green Berets and anti-Castro militants who were training that night on 9 March, 1961, managed to secure the crash site and eliminate all four survivors (albeit with heavy casualties in the process), though most of physical evidence the incident occurred was destroyed, though after-action reports, a few computer systems, a man-portable coilgun and photographic evidence were preserved, which proved to be useful 14 years later in the UN Convention on Extraterrestrial Interference. This lead to the formation of the United Nations Extraterrestrial Investigation Committee in secret, with the intent of investigating the Incident, preservation of the evidence and study of the captured technology, which had side-effects as you will now see. Unknown to the Americans or the rest of the world, prior to being killed, one of the survivors sent an emergency transmission to their nearby military outpost in Alpha Centauri (which took four years to arrive, and months to spread across the Grand Hegemony of Fanghdar (the name of their government and Fanghdar being their origin world and a hypothetical moon of the real life HD 37124 c, which the human designation following the discovery is HD 37124 c m XVIII (the planet has 18 moons, Fanghdar being the 8th moon in terms of distance to the planet's core and Roche limit), and I say months because of the wormhole network connecting their fledgling (but already dangerous) interstellar civilisation, fledgling because the furthest presence they have is in Alpha Centauri, although they do have a newly founded colony in a habitable moon of Gliese 876 b), and two years they spend preparing to invade us (and bringing in spacecraft with construction materials to last for a minimum of either 27 years or 57 years, I cannot decide and this is counting the 7 year trip to Earth, because antimatter beam core engines), which leads to interesting side-effects due to butterflies as previously mentioned. Kennedy survives assaasination, although Vietnam still intensifies, but not to OTL levels, which results in Nixon winning against LBJ, ARPANET comes online two years earlier, along with CYCLADES two years later, and of course, by 1975, their research vessels begin intensifying their observations and also begin to establish a permanent presence in our Solar System (including Earth, although outposts on Earth are on low priority to them until they can establish infrastructure to secure natural resources elsewhere in the Solar System later to be used against us), and eventually, as their research efforts intensify and governments begin to become worried, combined with the first attempts to form pro-extraterrestrial insurgents, the UN Convention on Extraterrestrial Interference begins in an unspecified location (originally it was supposed to be the UN HQ, but then I realised it would get so much media attention, now it is a base in Djibouti, at the time a French colony, known as Base Aérienne 188), and the convention results in the formation of the United Nations Extraterrestrial Response Unit (UNERU), which is basically a more realistic version of XCOM, on 30 June, 1975, along with the invocation of Article 47 of the UN Charter, and the integration of the UNEIC into UNERU's R&D Division (more on it later), with 1 July, 1975 being when operations under the organisation start, which is when the novel known as Skies Above Earth (authored by me) starts.
Here are the organisation's subdivisions:
- UNERU Research and Development Division (est. 1961 as the United Nations Extraterrestrial Investigation Committee (UNEIC for short)) - Conducts UNERU's R&D on reverse-engineering extraterrestrial technology.
- UNERU Manufacturing Division (est. 1980)* - Manufacutures military equipment derived from extraterrestrial technology.
- UNERU Public Relations Division (est. 1976) - Negotiates contracts and handles recruitment of new personnel and officers, without having to rely on the armed forces of UN Security Council member nations (permanent or otherwise).
- UNERU Counter-Terrorism Bureau (est. 1975) - Roots out extraterrestrial infiltrators and conducts counter-terrorism and counter-insurgency operations pro-Extraterrestrial terrorist groups and sympathisers.
- UNERU Aerospace Forces (est. 1975 as UNERU Air Forces) - Shoot down extraterrestrial craft (early and mid war); establish both orbital and atmospheric dominance and provide tactical support to UNERU forces (late war). They are normally filled with personnel from the nation they are stationed in, and are subordinate to a national command, which depends on the nation you are stationed in.
- UNERU National Commands (est. 1975) - Controls UNERU's Rapid Response Units, mainly used to secure the majority of crashed and landed extraterrestrial craft, and assault small extraterrestrial bases worldwide, each team hosting personnel from the nation it is stationed in.
- UNERU Regional Commands in North America, Central America, South America, Western Europe, Eastern Europe, Scandinavia, Middle East, Norh Africa, West Africa, South Africa, East Africa, Central Asia, South Asia, East Asia, and Oceania (est. 1975) - Controls regional task forces composed of various personnel from the 15 members of the UN Security Council (later extended to the rest of the UN), normally used to secure larger extraterrestrial craft, attack larger extraterrestrial bases worldwide (later extended to the rest of the Solar System), and respond to extraterrestrial raids on populated areas, with major cities given top priority, as well as centres of government.
- UNERU Global Command (est. 1975) - Controls the entirety of UNERU operations worldwide (later extended to the rest of the Solar System) and answers only to the UN Security Council, via the Military Staff Committee (which is the intent of the question at hand), led by The Commander (whose details still need to be further fleshed out).
NOTE: The asterisk refers to proposed dates of establishment, meaning the time the UNERU Manufacturing Division is established is undecided.
Alright, so based on this: could UNERU realistically need to be subordinate to the Military Staff Committee or directly to the UN Security Council?