ver since the inauguration of U.S. President Donald Trump in January, the world has been hypnotized by the prospect of a cease-fire in Ukraine. It is easy to see why. The election of an American president who wanted to act as a Ukraine broker rather than a Ukraine backer was seen as an opportunity to disrupt the status quo and stop the bloodshed.

But effective wartime diplomacy requires applying the right amount of leverage—sticks and carrots—on the right parties, under time pressure. Trump introduced the final factor by promising a swift outcome, and when that proved impossible, unsuccessfully threatening to walk away from negotiations altogether. But he failed when it came to rewards and punishments, wielding all the sticks against the country that was attacked while reserving all the carrots for the attacker. He railed against Ukraine, blaming it for the war, and at one point suspended assistance to its military. Meanwhile, he praised Russian President Vladimir Putin.

As a result, the world is no closer to meaningful negotiations now than it was when Trump won the U.S. presidential election in November. Countries have heard and seen a lot—Moscow’s pro-Trump messaging, Kyiv’s embrace of talks, Europe’s American outreach, and all the shuttle diplomacy. But these were less bridges to peace than attempts to flatter the U.S. president: the goal was not to end the war, but to bring Trump closer to one side and prevent him from sliding to the other.

Trump’s quest, however, was always going to be difficult. The stark reality is that neither Russia nor Ukraine has much of an incentive to stop the fighting. Moscow has built a wartime economy that allows it to keep fighting—and makes it hard to stop doing so. Ukraine is in no mood to compromise on its sovereignty, and its military remains strong enough to keep mounting an effective defense. As a result, for now, a cease-fire in Ukraine is impossible.