Have we forgotten Clausewitz? War is a mere continuation of policy by other means. (longer quote at end of post)
Russia's invasion of the Ukraine was the result of policy / politics. The same goes for the war in Sudan or Gaza, or any other war you care to name. The facts of policy lead to the facts of war -- how bad a war is going to be; how long, how short, how ghastly, etc.
Given our mixed primate heritage (big bright brain, willingness to kill, etc.) humans are and always have been capable of waging war using whatever means are at hand -- sticks, rocks, bullets, bombs, nuclear devices...
Getting back to policy, though. Sometimes policy can sound quite lunatic: buying Greenland; bringing Canada (kicking and screaming) into the American union of states; Germany acquiring the grain fields of Ukraine and Russia as well as its oil fields. The European powers liked the policy of owning everything as soon as Columbus got back from his first trip. We Americans established the policy of Manifest Destiny early on, which led to a long stretch of wars on various groups.
The goods of the planet are not evenly distributed, and we, greedy bastards that we are, generally take it easy, but we take it (if at all possible) from others who just happen to be sitting on it. Like the residents of Congo who find themselves witting on suddenly desirable cobalt. A world power hasn't stepped in yet to seize it, but local entrepreneurial entities are busy taking it and leaving a mess behind. (Belgium seized a good deal of the riches of the Congo while they had it in their grasp. Cobalt and uranium were of less interest than rubber, at the time.)
Gun Boat diplomacy is not a contradiction in terms. Powerless nations -- Nepal, say -- can try to be a diplomatic intermediary, but the diplomacy of nations with gun boats will be more 'effective'. The US or China can be much more persuasive.
I don't like it, but that's the way it is. I admire the peace policy of Quakers, the Fellowship of Reconciliation, or the Women's International League for Peace and Freedom, but they don't sway national policy much.
Clausewitz (1780–1831) We see, therefore, that War is not merely a political act, but also a real political instrument, a continuation of political commerce, a carrying out of the same by other means. All beyond this which is strictly peculiar to War relates merely to the peculiar nature of the means which it uses. That the tendencies and views of policy shall not be incompatible with these means, the Art of War in general and the Commander in each particular case may demand, and this claim is truly not a trifling one. But however powerfully this may react on political views in particular cases, still it must always be regarded as only a modification of them; for the political view is the object, War is the means, and the means must always include the object in our conception.