The US and Russia both claim to be fighting ISIS militants in Syria, but their ultimate goals are not the same. Russia supports the Assad regime, while the US is backing rebels in Syria's civil war. The US views Iran as a hostile power, while Russia calls it a partner. As they try to avoid major conflict, tensions grow hot and cold — heating up recently with airstrikes against controversial targets. Meantime, the Trump White House is divided over what the Pentagon should do. We update politics, diplomacy and the military options.