Because, just like with Israel, Ukraine is not self-sufficient militarily. If the U.S. pulls aid, Russia wins the war. It is, by definition, a proxy war - at least on the American-Ukrainian side.

If America pulled aid or gave Ukraine a firm timeline, Ukraine would lose all leverage in negotiations. And as long as American guns, bombs, and dollars are flowing into Ukraine, Ukraine will not settle for the status quo.

A better way to think of the negotiations is that Trump and Putin are negotiating the post-war situation for America to agree to pull support to Ukraine.