US and Central Powers sign peace treaty.

War between US and Central Powers end, and US leaves Entente.

The main reason behind the US joining the war was the thaumaturgic revolution and public outrage over the Central Powers 'atrocities' (most of which were caused by war psychosis), and - which was the main trigger - Central Powers resuming the unrestricted submarine warfare. Which happened mostly because the US started supporting Entente.   The peace initiative and the relative tameness of the Peace with Honour that Kaiser wanted (plus the fact that German war criminals were to be judged by an international tribunal - just like those from other countries participating in the war) was enough to fix the Central Powers PR worldwide. Including the United States.   Other than that US had little to have disputes over with Central Powers. The peace treaty between them was achieved as the first one, and while United States representatives were still participating in the Congress, the US participating in the Great War officially ended.