Military action should be, and usually is, the last resort. The U.S. can impose various sanctions on Russia, including freezing assets of individuals and companies, banning exports of technology, and restricting financial transactions with Russian banks. All of this, and more, hurts Russia's economy, and they are already hurting enough. That, probably more than the threat of violence, would keep Russia from invading Ukraine further.
As for China, if they were going to invade Taiwan, they would have already done it while Biden was president. They won't do it now that Trump is. And, they have too much to lose economically.
Europe has had the time to rebuild their military for decades. They just haven't because they've come to rely on the U.S. too much. As the U.S./Trump makes clear to them that we are not going to bail them out of their own messes, they'll be forced to rebuild their militaries.
"Waiting" for a perfect peace deal that "lasts" also means more U.S. treasure spent on an endless foreign war with little to nothing for the U.S. to show for it. Sound familiar? I think we're done with that. Trump is saying either end the war now or you're on your own.
