BEIRUT — Turkey deployed anti-aircraft guns, rocket launchers and other weapons along its border with Syria on Thursday, a military buildup that came as world powers showed new urgency to resolve the crisis before it ignites the region.
Turkey, once an ally of Syria, has been one of the strongest critics of Syrian President Bashar Assad, and tensions between the two countries spiked following the downing of a Turkish military plane last week.
A small convoy of Turkish military trucks towing anti-aircraft guns entered a military outpost in the border village of Guvecci, which faces a Syrian military outpost, according to TRT television video.
Anti-aircraft guns also have been deployed elsewhere along the border. Some trucks were seen carrying self-propelled multiple rocket launchers, the video shows.
Much of the violence that has gripped Syria since the uprising began in March 2011 has been sanctioned by the Assad government to crush dissent. Activists say more than 14,000 people have been killed.
But rebel fighters are launching increasingly deadly attacks on regime targets, and several massive suicide attacks this year suggest al Qaeda or other extremists are joining the fray.
Amid the buildup on the border, a bomb exploded in central Damascus on Thursday near a busy market and the country's main justice complex, wounding at least three people, damaging cars in a parking lot and sending a black cloud rising above the Syrian capital. It was not clear who was behind the bombing.
State-run TV said the bombing occurred at 1 p.m. in the parking lot of the Palace of Justice, a compound that houses several courts. The site is near the capital's famous Hamidiyeh Market, an area crowded with families stocking up on food and other supplies for the weekend.
The government blamed the attack on terrorists, the term it uses to describe rebels. Syria prevents journalists from working independently, making it difficult to verify accounts from either side in the conflict.
Ties between Turkey and Syria have not been this low since the late 1990s, when the neighbors almost went to war. Tensions ran high in the 1980s and 1990s as Turkey developed military ties with Israel and Syria sheltered Turkish Kurd guerrilla leader Abdullah Ocalan.
Now, Turkey is hosting civilian opposition groups as well as hundreds of military defectors who are affiliated with the rebel Free Syrian Army.
Syria insists the Turkish military plane it shot down on June 22 had violated its airspace. Turkey says the jet had unintentionally strayed into Syria's airspace and was inside international airspace when it was brought down over the Mediterranean.
The search for two missing pilots continued in Syrian waters but hopes for their survival are dim, Turkish authorities said. The Turkish military said search teams have found some pieces of the plane as well as equipment belonging to the pilots.
World powers will meet Saturday in Geneva for talks on Syria, but few observers expect a major breakthrough. Syria has the protection of Russia, a veto-wielding member of the U.N. Security Council, and so far has been impervious to international pressure.