Syrian forces have continued attacks on areas around Damascus, as they try to push back against rebel attempts to close in on the capital.

Opposition activists say government forces shelled Damascus suburbs Monday, a day after carrying out deadly airstrikes and rocket attacks against rebel-held areas.

Fighters opposed to President Bashar al-Assad have been trying to secure a perimeter around Damascus from their strongholds on the outskirts of the city.

Meanwhile, the U.S. State Department says it is “hopeful” NATO will approve a plan to deploy Patriot missiles near Turkey's border with Syria. Turkey has asked the alliance for the missiles in order to bolster its air defenses.

A senior State Department official said Monday that if NATO signs off on the plan, it will likely still be “a matter of weeks” before the missiles are deployed. NATO foreign ministers are meeting Tuesday and Wednesday in Brussels.

Syrian ally Russia has warned against the missile plan, saying it would not promote stability in the region.

Russian President Vladimir Putin is due to meet with Turkish Prime Minister Recep Tayyip Erdogan for talks Monday in Istanbul. The two sides have close trade ties, but remain opposed on their stance toward Syria.

Tensions between Russia and Turkey escalated in October when Turkey forced a Syrian passenger plane traveling from Moscow to land in Turkey because of suspicions it was carrying military equipment. The move outraged Russia, which said the plane was carrying legal radar parts.