So thanks to @AndyD273, I am now able to provide a coherent scenario of the situation I proposed earlier. So, here goes nothing....
Brief summary first: Pakistan falls into a civil war, followed by a group of Iranian terrorists stealing a nuclear device. Trump is reelected, inauguration day results in the stolen nuclear device going off. Secretary of State is later inaugurated as POTUS, and tries to start WWIII. He is deposed and killed in a coup d'etat, which results in California leaving the Union, along with Washington and Oregon (who later form Cascadia), and ending with Texas. At the same time, an armed insurrection emerges in the remaining US States, some of which side with the insurgents, and some which side with Mattis. The result is chaos. Now for the big details.
In late 2019 (originally late 2017), Pakistan falls into a civil war following anti-government protests turning violent and later spawning an insurrection. This results in its nuclear arsenal being vulnerable to terrorists who might take advantage of the situation. Months later, the Pakistani government a missing 40 kt nuclear device from Pakistan, which concerns the international community. Efforts begin to search for the missing warhead. Meanwhile, in the US, Trump is barely elected to a second term in office by the electoral college (which worsens an already problematic political divide).
On inauguration day, the stolen 40 kt nuclear device is detonated on Washington DC, killing Trump, Pence, most of Congress, the Supreme Court and the majority of Trump's cabinet. 258,260 casualties are reported initially, followed by at least an additional 210,000 deaths by radiation poisoning. Tillerson, Mattis, Perry and Carson are all that remain. Tillerson is inaugurated as POTUS in the temporary capital of Philadelphia, whom vows to bring vengeance on the people responsible for the destruction of Washington DC. Just as Tillerson is about to order a nuclear strike, Mattis initiates a military coup d'etat against Tillerson on the 2nd of February of 2021, fearing the outbreak of WWIII and the destruction of the US by Tillerson. Tillerson is killed, and Mattis forms the office of the Secretary of General Affairs, weeks later, with him filling the role, and Joseph Dunboard (former Chairman of the Joint Chiefs of Staff) takes the office of President, now purely symbolic. The new Mattis government, prior to the creation of the office of Secretary of General Affairs, begins an investigation into who is responsible for the attack.
However, in response to the coup, angry Americans protest against the new Mattis government, who responds with lethal force on American protesters, which later become armed insurrectionists. Some state governors later join the insurrection, as some National Guard units turn on Mattis, while the Western US decides to leave the Union, forming the Cascadian Republic and the Republic of California respectively. Texas quickly joins in and declares the Second Republic of Texas. In the remaining US states, some of the armed insurrectionists begin to organise themselves into multiple groups with the assistance of some local National Guard units and state governors, while others, already old political parties, became part of the insurrection:
- New Sons of Liberty (Libertarians, mostly concentrated in the remainder of the American Southwest)
- Free America Army (old Tillerson loyalists, whom have fled into the countryside after the Philadelphia Putsch, and Tillerson's death during that time frame)
- United Democratic Front (a coalition of armed Democratic and Republican members in the US)
- Popular Front (A left-wing insurgency concentrated in the left-leaning US states)
- People's Liberation Army of America (A small, Maoist terrorist group)
- Communist Party of the United States of America (an old third party before the Last Inauguration and now a terrorist group)
- Free Dixieland Movement (Neo-Confederates that have banded together to fight Mattis' government, using the opportunity to restore the Confederacy)
- American Nazi Party (the old Neo-Nazi Party in the United States, now taking advantage of the chaos to grow into a fully armed insurrection).
By late 2021, with some National Guard units and even Army divisions fighting Mattis' government side by side with the insurgents, and the independence of California, Cascadia and Texas, the Second US Civil War begins.
So, which major foreign powers are likely to get involved in terms of supplies, funding and aid to either side in in the conflict?
NOTE: This is Part I of a series of questions I plan to deal with regarding foreign interference in a hypothetical Second US Civil War. Part II will deal with a more direct intervention by foreign powers, while Part III will detail UN involvement.
WARNING and DISCLAIMER: CPUSA and the ANP are ACTUAL political parties as of 2017, for those of you not living in the States or in case you are too lazy to do the research. In my case, I had to do some research. This post is purely intended to ask questions in regards to the creation of a fictional world, so do not take this seriously.