Answer:
Yes
Explanation: (warning: I am really bad at explaining things though, so I hope you still understand what I am trying to say.)
Countries have been fighting with each other for generations. doesn't matter if it's to prove who is stronger, to gain territory or for revenge.
One thing is certain:
You need Allies if you're going to do something big like take part in something as big as a war. And that is where my example comes in:
Example: Russia has been attacking Ukraine so they can have it back as their territory.
Now if you look at the difference in size and army you would think "why has Russia not won yet?"
It is simple: Russia is fighting with old equipment while Ukraine is fighting with new and stronger equipment donated to by other countries.
So, in conclusion: Yes, Other nations and countries should be allowed to engage in the affairs of other countries. because most of the great countries we have today would not have been able to develop the way they have (even if they have been dark) without the help of other countries. Anybody can do anything, but they can do more and do better with the help of other people or in this case, other countries.
hope this helps. sorry if my explanation is bad. things always sound better in my head but whenever I say things like try to explain they turn out wrong then what I mean.
imma stop rambling now... but anyways hope it helps. sorry if it did not.