When the actually vital interests (Soviet missiles in Cuba were a vital threat for the USA, and American missiles in Turkey were a vital threat for Russia) actully collide - then, yes, the war is inevitable, and even UN can't prevent it. But, if there is a possible mutually acceptable solution (like Russia removes missiles from Cuba and the USA removes missiles from Turkey), then, it's much safer and cheaper to find it in a discussion, rather then in a local conflict, proxy war, or even in the actual all-out war . The world in which Russia could prevent Clinton's agression against Serbia, or America could prevent Putin's SMO in Ukraine just by a signing a paper, without sending actual weapons and killing actual human beings, might be much more safer for everyone.