The United Nations' nuclear watchdog has toughened its stance toward Syria, warning that lack of cooperation by Damascus won't prevent the publication of a critical report on Syria's nuclear program. The challenge marks a departure in the International Atomic Energy Agency's nearly three-year effort to gain access to several Syrian sites by shifting the burden of proof to Syria, an ally of Iran, to demonstrate it is fulfilling its international nuclear obligations and isn't pursuing nuclear weapons. In a November letter to Syrian Foreign Minister Walid al-Moallem, IAEA Director General Yukiya Amano demanded that Syria cooperate with the IAEA's investigation of an alleged former nuclear facility at Dair Alzour, according to three Western diplomats familiar with the letter. Otherwise, he indicated, the agency would draw and report its own conclusions as to whether the country's atomic program is in international compliance with the Nuclear Non-Proliferation Treaty, based on the evidence it has already, without Syrian cooperation, according to these people. The IAEA could release its findings as early as late February, when an IAEA report on Syria's nuclear activity is expected, roughly two weeks before the agency's board of governors meets on March 7.