The Security Council had approved in April the deployment of 300 unarmed observers to monitor a ceasefire that was called for in a peace plan negotiated by Kofi Annan, who was then acting as the U.N.-Arab League envoy. But the ceasefire fell apart, the fighting continued and the UN scaled back its observer force to 150.
Its numbers will be reduced to 100 by August 14, the U.N.'s Department of Peacekeeping said Thursday.
The United States has provided only nonlethal aid such as communications equipment. But recent actions and rhetoric hint at more action.
President Barack Obama signed a covert directive authorizing U.S. support for Syrian rebels, U.S. officials told CNN last week. The secret order, referred to as an intelligence "finding," allows for clandestine support by the CIA and other agencies.
John Brennan, Obama's chief counterterrorism adviser, said Wednesday that all options, including the possibility of imposing a no-fly zone, remained under consideration.
Iran, a supporter of the al-Assad regime, hosted a conference on the conflict Thursday in Tehran.
Among the representatives of more than two dozen countries attending were the foreign ministers of Pakistan, Zimbabwe and Iraq, state-run Islamic Republic News Agency said. China and Russia, also allies of Damascus, were among the nations to send delegates to the conference.
But nations critical of the regime, such as the United States, France, Britain, Turkey, Saudi Arabia, and Qatar, were absent.
A statement from the conference emphasized "the necessity of pursuing political solutions based on national dialogue as the only way to resolve the Syrian crisis with the main objective of bringing the violence to a total end and encouraging the two sides to prepare the ground for the national dialogue."
The statement championed "non-intervention in domestic affairs of other countries and the respect of their national sovereignty and territorial integrity."
It also expressed "serious concern over the entry of known terrorist groups and sects into the Syrian conflict and seriously warning of the spread of terrorism and its dire consequences on the peace and security of the region." Syria has consistently blamed violence in the country on "terrorist groups."
Iranian officials, meanwhile, visited capitals in the region to discuss Syria and get help to free dozens of Iranians abducted over the weekend by rebels in Syria.
Iranian media initially reported that the 48 captives were pilgrims on a visit. In a televised video later, Syrian rebels claimed responsibility for the kidnapping, saying the captives were not pilgrims, but were members of Iran's Revolutionary Guard. Salehi said they included retired members of the Guard, the semi-official Iranian Students' News Agency reported Wednesday.
Three of the 48 Iranians were killed during shelling in the Damascus suburbs, the LCC said.