Troops gain suburb near Damascus

BEIRUT - Syrian troops pushed forward with their offensive against rebels Saturday, capturing a suburb near the Damascus international airport as the U.S. warned that the alleged use of chemical weapons by President Bashar al-Assad's forces and the involvement of the Iranian-backed militant group Hezbollah in the civil war threaten to put a proposed political settlement out of reach.

The United States and Russia have been pressing for a peace conference to end Syria's civil war in Geneva, but prospects for that have been dampened after a series of regime battlefield victories and hardened positions by both sides as the death toll from the more than two-year-old conflict has surged to nearly 93,000.

President Obama's decision last week to send lethal aid to Syrian rebels and the deepening involvement of trained Shiite fighters from Lebanon's Hezbollah group also has raised the stakes, setting up a proxy fight between Iran and the West that threatens to engulf more of the Middle East.

The U.S. reversal after months of saying it would not intervene in the conflict militarily came after Washington said it had conclusive evidence the Syrian regime had used chemical weapons, something Obama had said would be a "red line."

Syria has denied the accusations, saying Obama was lying about the evidence to justify his decision to arm the rebels. Syria's ally Russia also suggested Saturday that the evidence put forth by the United States of the use of chemical weapons doesn't meet stringent criteria for reliability.

U.S. Secretary of State John Kerry was quoted in a statement as saying the United States continues to work aggressively for a political solution with the goal of a second Geneva meeting. But "the use of chemical weapons and increasing involvement of Hezbollah demonstrates the regime's lack of commitment to negotiations and threatens to put a political settlement out of reach," he said in a telephone conversation Friday with Iraqi Foreign Minister Hoshyar Zebari.

Russia's Foreign Minister Sergey Lavrov said the U.S. evidence does not include guarantees that it meets the requirements of the Organization for the Prohibition of Chemical Weapons. He said the organization specifies that samples taken from blood, urine and clothing can be considered reliable evidence only if supervised by organization experts from the time they are taken up to delivery to a laboratory.

The OPCW is the autonomous body for implementing the international Chemical Weapons Convention that went into effect in 1997. Its website says Syria is one of six countries that have not signed or acceded to the convention.

Lavrov, after meeting with his Italian counterpart Emma Bonino, scoffed at suggestions that Assad's regime would use chemical weapons in light of its apparent growing advantage against the rebels.

"The regime doesn't have its back to the wall. What would be the sense of the regime using chemical weapons, moreover at such a small quantity?" he said.

Syria's conflict started with largely peaceful protests against Assad's regime in March 2011 but eventually turned into a civil war.

Russia has blocked proposed U.N. sanctions against Assad's regime and acknowledged last month that it has contracted to supply advanced S-300 air-defense missiles to Syria. But President Vladimir V. Putin and other officials say the policies do not constitute overt support for Assad.

The statements by Moscow and Washington came days before a summit in Northern Ireland among the Group of Eight leading industrial powers. Obama is expected to push Britain and France to take similar action to arm the rebels when talks open in Northern Ireland.