ISTANBUL- Russian President Vladimir Putin warned Monday that any deployment of US-made Patriot missiles on Turkey’s volatile border with war-ravaged Syria would exacerbate tensions, and said the two countries had failed to overcome their sharp differences on the conflict.

“Creating additional capabilities on the border does not defuse the situation but on the contrary exacerbates it,” Putin told a press conference with Turkish Prime Minister Recep Tayyip Erdogan after talks in Istanbul.

He was speaking on the eve of a NATO meeting in Brussels that is expected to rule on Ankara’s request for the deployment of the Patriots on the border with Syria, with Turkey fearing a spillover of the near 21-month conflict.

“You know, as they, say if a gun is hung on the wall at the start of a play then at the end of the play it will definitely fire,” Putin said. “Why should we need extra shooting at the border? We are urging restraint.”

“Russia and Turkey for the moment cannot find a mutual approach on the methods of how to regulate the situation in Syria. But our assessment of the situation completely coincides,” the ITAR-TASS news agency quoted him as saying.

Putin said his country was not a defender of the Assad regime. “We are not inveterate defenders of the current regime in Syria,” Putin said. “I’ve already said it many times. We are not advocates of the incumbent Syrian leadership. Other things worry us, like what will happen in the future?”

Meanwhile, the regime of Syrian President Bashar al-Assad vowed Monday it would never use chemical weapons against its own people.

The statement from Damascus came after US Secretary of State Hillary Clinton warned Assad that the use of chemical weapons constituted a “red line” and US media cited anonymous officials as saying they had detected the Syrian military moving the arms.

“Syria confirms repeatedly it will never, under any circumstances, use chemical weapons against its own people, if such weapons exist,” a Syrian foreign ministry official said in televised remarks.

“This is a red line for the United States,” Clinton said after meeting Czech Foreign Minister Karel Schwarzenberg, during which they talked about concerns over Syria’s chemical weapons stockpile.

“Once again we issue a very strong warning to the Assad regime that their behaviour is reprehensible. Their actions against their own people have been tragic,” she told a joint news conference with her Czech counterpart.

In an exclusive interview with AFP, meanwhile, Arab League chief Nabil al-Arabi said Assad’s regime was in danger of collapse “anytime” as the opposition gained ground on the military and political fronts. “Facts on the ground indicate very clearly now that the Syrian opposition is gaining, politically and militarily. Everyday they are gaining something,” Arabi said.

On Monday, an air strike killed at least 12 people - eight rebels and four civilians - and wounded more than 30 in the northeastern town of Ras al-Ain on the border with Turkey, the Syrian Observatory for Human Rights said.

The warplane hit the Mahata district “controlled by the (jihadist) Al-Nusra Front, Ghuraba al-Sham and other rebel battalions,” the Observatory said.

Meanwhile, a UN news agency said Monday that the United Nations is to pull non-essential staff out of Syria because of the growing conflict dangers and is restricting travel for those remaining.

A quarter of the 100 international staff still in Damascus could leave this week, some staff could be moved out of the northern city of Aleppo and travel outside the capital will be restricted, the IRIN agency quoted UN humanitarian officials as saying.

Syrian foreign ministry spokesman Jihad Makdisi, a well-known advocate of President Bashar al-Assad’s regime, has resigned and is headed for London, the Syrian Observatory for Human Rights said on Monday.

“Makdisi was pressured by people inside the presidential palace, but not the president himself, to resign. He is now on his way to London,” Observatory director Rami Abdel Rahman told AFP, adding that he had left from Beirut international airport.