President Donald Trump, after repeatedly promising to quickly end Russia's war on Ukraine, has changed his tune and his attitude dramatically.

But halting progress, ever-more deadly drone attacks and unmoving negotiating positions seem to have taken their toll. On Thursday, Trump used a striking analogy to concede the warfare was nowhere near over, and that he did not, at that moment, feel it was best to intervene.

President Donald Trump said Thursday that it might be better to let Ukraine and Russia "fight for a while" before pulling them apart and pursuing peace, even as Germany's new chancellor appealed to him as the "key person in the world" who could halt the bloodshed by pressuring Russian President Vladimir Putin.