This is 100% Trump. He thinks this is a big foreign policy win that he can carry into the mid-terms.

Of course, ending the war means convincing Russia to back down from the fight that they started, and the US no ability to do that because Trump still keeps trying to treat Russia like a friend. So any pressure they put on them will be meaningless. Meanwhile any pressure they put on Ukraine will basically amount to “End the war on Russia’s terms, or fight it without our help”, which is just a choice between two equally terrible options.