The United States and Russia announced an agreement on Monday for a partial truce in Syria , though the caveats and cautious words on all sides underscored the obstacles in the way of the latest diplomatic effort to end the five-year-old civil war. Under the terms of the agreement, the Syrian government and Syria ’s armed opposition are being asked to agree to a “cessation of hostilities,” effective this Saturday. But the truce does not apply to two of the most lethal extremist groups, the Islamic State and the Nusra Front, raising questions about whether it will be any more lasting than previous cease-fires. The agreement calls for the Syrian government and the […]