Syrian boys look at a destroyed tank near a damaged mosque in the city of Azaz. (Ben Hubbard, Associated…)
WASHINGTON — Conceding that a peaceful resolution in Syria now appears remote, President Obama warned Monday for the first time that use or movement of chemical or biological weapons by forces loyal to President Bashar Assad would constitute a "red line" for U.S. military intervention.
Obama acknowledged his frustration that diplomacy has done little to protect civilians or stem the growing bloodshed in the 17-month conflict. International efforts to persuade Assad to step down, to negotiate an effective cease-fire or to facilitate a political transition have been unsuccessful.
"At this point, the likelihood of a soft landing seems pretty distant," Obama said in a brief, unscheduled news conference at the White House.
He spoke as activists in Syria reported the killing of at least 127 people Monday in urban street battles and other clashes between rebels and government forces. Activists also described a grisly discovery of at least 10 bodies that showed signs of torture in the Qaboun area of Damascus, the capital.
In Aleppo, Syria's largest city and its commercial hub, a government airstrike destroyed an apartment building and killed at least 10 people, including women and children, activists said. Among the dead was a Japanese journalist; a video posted online showed her body in a field hospital.
Obama said he has not "at this point" ordered the U.S. military into action. But he said his administration has "put together a range of contingency plans," including a response if it appears Assad's forces are preparing to use poison gas or biological weapons in a bid to stay in power.
"We have communicated in no uncertain terms with every player in the region that that's a red line for us, and that there would be enormous consequences if we start seeing movement on the chemical weapons front or the use of chemical weapons," Obama said. "That would change my calculations significantly."
The administration has provided communications gear and other nonlethal aid to the rebels, but it has rejected calls to arm the main rebel force, the Free Syrian Army, or to set up a no-fly zone to prevent Syrian warplanes from attacking civilian areas. U.S. officials say they are cautious, in part, because the ragtag coalition of militias includes some aligned with Al Qaeda and other extremist groups.
Obama said the danger from Syria's weapons stockpiles "concerns our close allies in the region, including Israel. It concerns us. We cannot have a situation where chemical or biological weapons are falling into the hands of the wrong people."
Syria is believed to have huge stockpiles of the sarin nerve agent, mustard gas and cyanide.
U.S. officials believe that Assad's government retains control of its weapons depots, but Obama offered a cautious response when asked if he thought that the stockpiles were safe.
"In a situation this volatile, I wouldn't say that I'm absolutely confident," he said. "What I'm saying is we're monitoring that situation very carefully."
Concern about the weapons began to rise in mid-July, when Israeli and U.S. officials reported that Syria might be moving some of the materials, possibly in preparation for their use or to safeguard them from advancing rebel fighters.
Israeli officials warned that they would not allow the weapons to fall into the hands of adversaries such as Hezbollah, the Syrian-backed Lebanese militant group.
U.S. officials hope to avoid any Israeli intervention, which could further inflame Syria's civil war.
Turkey's foreign minister, Ahmet Davutoglu, urged the United Nations to help as Syrians flee to neighboring countries, according to the Anatolian Agency, the official news outlet. Turkey has registered nearly 70,000 Syrian refugees so far, he said, and the number is growing.
A Times staff writer in Beirut contributed to this report.