If I were the president of Ukraine, I may go to war and I may also not go to war and many things will determined my decision. These factors that determine my decision are;

What will be the consequences of not involving in the world?
If the consequences will be continuous intimidation and slavery to the other country, I will fight till the last citizen of my country is wipeout.

But if the consequences is not related to suffering and slavery, but just political alignment. I will just back off and maintain peace in my country.
It also depends on the kind of advice the president get. Many people must have promised him ammunition and man power