If USA has riots and Trump is president ...and if i was Putin i would call my best buddy Xi Jinping and tell him to prepare the army and get ready for invasion...
Putin: - Xi it's time to visit America !
https://www.youtube.com/watch?v=c5BL4RNFr58war isn't as easy and cheap as you think it is. it requires a lot of resources that could cripple the economy even the one who started the war. I doubt any of the countries right now would risk their economy being ruined just because there are riots happening in America.
World leaders are not that dumb to think about war and end the world. Because once you started a war it means that many explosive weapons of Mass Destruction will hit each and every country. Do you think that will make those riots or conflict between the country to stop? Before you think of a war, that's right that you need to have a lot of resources so that you will not be outpowered by other countries.
Leaders should help each other surpass and overcome their economic crisis, they should help each other for the sake of its citizens. All lives matter and i know that some people are scared to death, that's why the governments should focus first on the Covid-19 pandemic and stop that war issues.
That will not help each and every one of us to become more stronger and united. Spending most of the government's budget for a war is not a worth it idea.
Invasion? I mean seriously? Invasion? We are way beyond that and there hasn't been an invasion of USA in centuries. The last "war" they probably had was their own civil war, and before that it was probably just UK independence thingy. This is USA we are talking about you do not invade them, you don't go to their continent and try to get a land from them. This is 2020 and there is no need for a land base war.
Sure there is some at middle east but they are not caught up with 2020 anyway, they are still acting like they live in 1200's with just guns instead of swords that is the only difference. So at the end of the day, Russia and China could go to "war" with USA but it would be more economical and social instead of being actual guns involved war. They could just cause a lot more uproar and riots with social media fake accounts stirring up stuff but that's about it.