If you're gonna do a Mexico analogy, do it properly.
Let's say Mexico has always had regions with a substantial population of Americans (not an ethnicity but bear with me). Let's say the US has pipelines to South America through Mexico. Let's say the US has port access to seas from within Mexico (I know, makes no sense but keep up).
So, the situation is that the US has vital economic and security interests in Mexico. Therefore they have an outsized influence on what happens in Mexico and its government, which is only prudent. However there's no hostilities, it's peaceful relations and Mexicans are not at all interested in fighting about it. They are developing their economy just fine, IT industry sector and grain exports. The US is trying to recover from a highly corrupt, failed state-status, and is working on developing trade and its economy. They have been trying to break free from exploitive and damaging economic influence from their historical adversary that operates international institutions to its advantage.
Things would have been just fine developing like that. But here comes China, the historical adversary. They start to push for including countries in North and South America into their military alliance. This is in spite of the fact that the alliance is obsolete, as the US isn't being adversarial or confrontational, but would still be a boon to China's military industry nonetheless. They succeed in getting Canada and other countries surrounding America to join. The US is unhappy and protests peacefully through diplomacy.
China presses on and wants now to include Mexico and Cuba (Georgia IRL), which is unacceptable for the US as that would critically disrupt its ability to develop the country if there's a conflict. They make this unequivocally clear. China wants to put missile bases and build military forces in Mexico. The US can't live with this, just the same as decades prior when China would not tolerate American missile bases in Mongolia.
China overthrows the Mexican government, starts arming Mexican forces and they attack American populated regions. THIS is when hostilities and armed conflict begins. The US sees where things are headed and decides to annex an American populated region in Mexico that grants port access (Crimea IRL).
Mexican forces destroy economic and trade infrastructure of the US. Tens of thousands of people will be killed and millions of Americans will flee out of Mexico into the US. The US is STILL trying to solve this diplomatically, and a peace agreement is signed. The key point of the agreement is that Mexico remain neutral with no military presence from either side. But China violated the agreement right away and continues to arm Mexican forces. The fighting escalates.
War breaks out. After much fighting, the US has annexed regions where they have economic and security interests for Americans, and will hold on to these new territories because their counterparts have lost all credibility. They will not be able to trust any kind of agreement. They will hold these positions, and eventually China will get bored and move on to a different conflict zone. After all, they are known for pulling this same shyt all over the world, particularly in the Middle East and Africa.
Now back to reality. You see, "sovereignty" in this context doesn't mean shyt, yet this is the straw idiot posters here keep grasping at. That shyt already been violated by America and Ukraine when they attacked Russians and their economic interests inside Ukraine. The US is the aggressor, and the rest of the world seems to agree because they continue to work with Russia while America and its Western allies continue to isolate themselves.