The Biden administration is mulling over America’s role in Syria’s ongoing conflict as the U.S. tries to break away from Middle East wars. But Vladimir Putin’s top diplomat already has been busy on the ground, trying to win support for a Syria approach that could establish Russia as a broker of security and power in the region. Syria is now fragmented among a half-dozen militaries — including U.S. troops — owing to a war that has killed and has displaced millions. Dealing with Syria’s war will test the Biden administration’s determination to focus on Asia and not the Middle East as its main foreign policy challenge.