This week saw a grim escalation in the conflict in Syria. The opposition there alleged government forces had used chemical weapons, killing hundreds, including women and children. The U.S. and others called for a UN investigation, with France’s foreign minister suggesting the use of force if the allegations are confirmed. A UN team is in Syria to investigate previous allegations of chemical weapons use, but it’s not certain they’ll be allowed to look into the newest ones, which the government denies. Syria’s chief international ally, Russia, after earlier suggesting the attack was staged by opposition forces, joined the call for an international investigation.