UN Secretary-General Ban Ki-moon on Tuesday sent a letter to Syrian President Bashar al-Assad to convey his concerns over chemical weapons.
Five people were killed and 20 others injured after an earthquake hit eastern Iran's South Khorasan Province Wednesday night, local media reported.
A magnitude 5.9 earthquake struck eastern Iran on Wednesday, 42 miles (68 km) north-northeast of Birjand, the U.S. Geological Survey reported.
Deputy Secretary of State William Burns met with UN-Arab League Joint Special Representative for Syria Lakhdar Brahimi and discussed with him the current situation in Syria in Washington.
NATO agreed to send Patriot missiles to Turkey to defend against a possible missile attack and voiced concern about reports that Damascus may be preparing to use chemical weapons.
Iran said on Tuesday it had captured a US intelligence ScanEagle drone in its airspace over the Gulf in the last few days, but the United States said there was no evidence to support the assertion.
Russian Foreign Minister Sergey Lavrov on Tuesday expressed concerns over NATO's possible deployment of surface-to-air Patriots missiles to protect Turkey from potential attack from Syria.
NATO foreign ministers on Tuesday approved Turkey's request for Patriot missiles to defend it from potential attack from neighboring Syria.
Iran captured a US drone that was flying in the country's airspace, its media reported on Tuesday.
Visiting Russian President Vladimir Putin said in Istanbul on Monday that Russia is not an advocate of the Syrian government.
US President Barack Obama on Monday warned Syrian President Bashar al-Assad of "consequences" in using chemical weapons in the Arab country's 21-month conflict.
Britain, France and Sweden have summoned Israeli ambassadors to protest Israeli Prime Minister Benjamin Netanyahu's decision to build 3,000 more houses in East Jerusalem and the West Bank.