OK!
Peace comes from opposing international aggression.
Show potential aggressors that their crimes will not be rewarded.
This has been the international consensus since the days of the League of Nations (betrayed by cowardice), was the original justification of the UN (see Korea), was the basis of US foreign policy since 1941, was the reason for NATO ... need I go on?
If you dont like it, then go ahead. You too are part of an old tradition you know, not limited to the US by any means.
Our leaders going back a century understood this, the keeping of the peace, as their first duty.
I recommend a decent background on the argument.
“The Cold War: A New History” John Lewis Gaddis
And - from 1950, laid out explicitly, with evaluated options (which is rare for these things)
https://irp.fas.org/offdocs/nsc-hst/nsc-68.htm