On Friday, a cessation of hostilities brokered by U.S. Secretary of State John Kerry last week in Munich is set to go into effect. Part of the agreement includes the delivery of urgently needed humanitarian aid to besieged areas. That part of the deal has begun. The other part? Not so much.Kerry explained the Obama administration’s position on Syria earlier this month in an interview with The Washington Post: “What we’re doing is testing [Russian and Iranian] seriousness,” he said. “And if they’re not serious, then there has to be consideration of a Plan B…. You can’t just sit there.” Russia’s intentions are of particular concern to the United States. Backed by the Russian military, the government has nearly surrounded Aleppo, the rebels’ most important base. The campaign has been bloody, forcing a new wave of Syrians to flee. With no appetite to send in U.S.ground troops, calls for a safe zone in Syria are getting louder. So far, the U.S. has said no. But with so few options left – and fears of Putin’s growing influence – Kerry’s hint may be a revised U.S. policy