The Washington Post Anne Gearan BRUSSELS — NATO agreed Tuesday to send new American-made air defenses to Turkey’s volatile southern border with Syria, a boost to an alliance member on the front lines of Syria’s civil war and a potential backstop for wider U.S. or NATO air operations if the situation deteriorates further. The alliance’s approval of Patriot anti-missile batteries represents NATO’s first significant military involvement in the 20-month-long crisis, even if it falls well short of rebels’ demands for help. NATO and U.S. officials insisted that the system is entirely devoted to defending Turkey and is not a precursor to a military intervention in Syria. The Patriots will provide no protection for Syrian civilians or rebels fighting to unseat President Bashar al-Assad. However, the system, likely to deploy early next year, could be repurposed as part of a wider air campaign or to provide air cover for action in Syria should NATO change its mind. Military experts said Patriots are as effective against aircraft as they are against missiles, and deploying the system at the border could be instrumental in quickly carving out a 25-mile buffer zone. The threat that a besieged Assad might resort to chemical weapons as rebels gain ground gave new urgency to NATO’s debate. Syria, which is party to the 1925 Geneva Protocol banning chemical weapons in war, has repeatedly insisted that it would not use such weapons, even if it possessed them. It has called the Patriot plan “provocative” and considers it a possible first step toward a no-fly zone, airstrikes or an invasion. For now, U.S. and NATO officials say the system is designed to bolster the NATO member most directly affected by the Syrian civil war, and nothing more. Although the alliance counts the 2011 Libya no-fly zone as a success, it opposes similar action in the Syrian conflict. The Obama administration also remains opposed to intervention in a civil war that has claimed as many as 40,000 lives, including at least 15 on Tuesday when mortar rounds slammed into an elementary school. “Turkey has asked for NATO’s support, and we stand with Turkey in the spirit of strong solidarity,” NATO Secretary General Anders Fogh Rasmussen said after approval by the 28-member alliance at a meeting in Brussels. “To the Turkish people we say, ‘We are determined to defend you and your territory.’ To anyone who would want to attack Turkey we say, ‘Don’t even think about it.’ ” Chemical weapons moved Syria is believed to have the world’s third-largest store of chemical weapons, along with medium- and long-range missiles that could deliver them inside or outside the country. The weapons, which can kill large numbers of soldiers or civilians, can also be delivered by aircraft. U.S. officials said Monday that satellite images showed Syrian forces moving chemical weapons into positions where they could be used more quickly. Although Rasmussen offered no specifics, U.S. officials said the White House and its allies are weighing military options to prevent or defend against a chemical attack. Continued