NATO's Secretary General says foreign ministers are expected to approve Turkey's request for Patriot anti-missile systems to prevent spillover violence from neighboring Syria.

NATO Secretary General Anders Fogh Rasmussen told CNN that NATO members will likely “respond positively” to the Turkish request. NATO ministers are meeting Tuesday and Wednesday in Brussels.

Turkey wants the anti-missile system to protect from possible Syrian attacks using chemical weapons. U.S. President Barack Obama warned Monday that he wants Syrian President Bashar al-Assad to know that using chemical weapons would be a “tragic mistake” resulting in consequences.

Syria's foreign ministry reiterated its previous rejections of the U.S. allegations. In a statement Monday, it said Damascus “will not use chemical weapons, if it had them, against its own people under any circumstances.”

Turkish Prime Minister Recep Tayyip Erdogan discussed the situation in Syria with Russian President Vladimir Putin Monday in Istanbul. Mr. Putin said he understands Turkish concerns about border security, but he cautioned that Turkey's request for the NATO alliance to deploy Patriot interceptor missiles near Syria could exacerbate the situation.

Turkey and its Western and Arab allies are calling for the ouster of Mr. Assad, who counts Russia as one of his few remaining allies.

The Syrian Observatory for Human Rights said Tuesday violence across the country killed 198 people on Monday. Syrian government forces bombed rebel positions in the northern town of Ras al-Ain, killing at least 12 people and prompting Turkey to scramble fighter jets along its southern border with Syria.