By Peter Apps
LONDON (Reuters) - Syria's warring sides might have struggled to get the foreign arms they want, but even before this week's apparent chemical attack both government and opposition were using ever more powerful conventional weapons.
On Wednesday, opposition forces accused the government of President Bashar al-Assad of killing hundreds with a nerve gas attack in the suburbs of the capital Damascus.
The government of Bashar al-Assad denied the charge, but with international condemnation mounting, analysts said it was becoming ever more likely that western states and their Gulf allies would finally get on with seriously arming the rebels.
What is certain, activists and analysts say, is that recent months have seen a move towards larger weapons, from bunker-busting bombs being used by Syria's air force to increased rebel use of captured tanks, artillery and rockets.
For now, there are few if any signs that high-profile talk of weapons supplies from Western and Gulf states to the rebels and from Russia to Assad have been followed through in anything like the quantities needed to shift the balance.
"Outsiders - both the West and the Russians - have been holding back," says David Hartwell, a former British Ministry of Defense official now Middle East analyst for IHS Jane's. "But in reality that may not matter as there are plenty of weapons within Syria, and the more jihadist opposition elements in particular seem to be really upping their game and using them."
Earlier this month, opposition fighters widely believed to include Al Qaeda-linked elements captured a major military air base at Mannagh near the border with Turkey. They also pushed deeper into the Assad government's ethnic Alawite heartland of Latakia.
While there is no sign the rebels have the capability to operate the government attack helicopters they claimed to have captured at Mannagh, analysts say online videos have shown them increasingly using T-54 and T-62 Soviet-built tanks.
The Free Syrian Army - as well as the Al-Qaeda affiliated al-Nusra Front and other groups - have also been using increasingly potent captured artillery. This has included Grad surface-to-surface rockets analysts say were vital to the Islamist-led push into Latakia.
FOREIGNERS HOLD BACK
As with militants in Iraq and Afghanistan, rebel fighters in Syria appeared to have become increasingly adept at designing their own weapons. One set of online videos shows rebel commanders showing off their "Hell Cannon", a 4-metre long rocket said to be capable of delivering 120 kg of high explosive more than 3 kilometers (1.9 miles).
One image showed one such launcher apparently built into an industrial digger, perhaps for stability. ( http://brown-moses.blogspot.co.uk/2013/08/diy-weapons-in-syria-syrian-opposition.html )
Pictures from within Syria also suggest Assad's allies Hezbollah are also improvising their own systems, increasing the payload capacity to make their basic handheld rockets carry more explosive.
Some foreign weaponry has continued to slip in, with ongoing reports of Chinese-manufactured handheld anti-tank and anti-aircraft rockets widely suspected to have been bought by Qatar, possibly from Sudan, for delivery to Islamist fighters.
Saudi Arabia has also provided some weapons, experts and foreign officials say. But long-touted shipments of military aid from Britain, France and the United States have never arrived.
When the White House announced in June that chemical weapons usage by Assad's forces had changed the strategic equation and that it would supply military support, officials suggested the first major shipment would arrive in August.
In reality, however, decisions were delayed by a lack of agreement in Congress. Even with some Congressional roadblocks now cleared, U.S. and other foreign officials see a growing reluctance to follow through on the talk, particularly as Islamist influence in the anti-Assad forces continues to grow.
As Western, Russian, regional and UN officials tried to tiptoe ever closer to some kind of Geneva-based peace talks, Moscow too appears to have held back on some of its more serious weaponry offers to the Assad government.
Foreign officials and analysts say there has so far been no sign of Russia moving to deliver on its offer of sophisticated S-300 anti-aircraft missiles. That offer, many analysts believe, was largely designed to block any suggestion that the West might impose a Libya-style no-fly zone.
With the likelihood of such action now seen much reduced - although that could change in the aftermath of Wednesday's reported chemical strike - Assad's air force now appears to have abandoned any thoughts of holding back its heavier weaponry.
BUNKER BUSTERS, ANTI-AIRCRAFT MISSILES
Most analysts believe Assad has probably received some new supplies of basic ammunition and artillery shells, possibly from Russia and almost certainly from Iran. In general, however, he is believed to be still largely relying on Syria's pre-war stockpiles.
Eliot Higgins, a UK-based blogger with the pseudonym "Brown Moses" who has emerged as an unexpected and largely self-taught expert on weaponry in Syria, says videos posted online after air raids show ever heavier weaponry being used.
"It's been going on for a while," says Higgins, whose work has been praised and used by rights groups such as Amnesty International. "We've been seeing some cluster munitions and incendiaries used since late last year. Now they seem to be using almost everything they have got, even if it's not always that effective."
Recent months, he says, have seen the first appearances of the S-25, an air-to-surface missile, and the also Soviet-built AS-14 Kedge, designed to penetrate military bunkers and perhaps used to target rebel tunnels and cellars.
Improved rebel anti-aircraft capability may also be forcing a change in tactics. As well as truck-mounted heavy machine guns, the rebels have also increasingly been seen with foreign-supplied Chinese-made FN-6 handheld MANPAD portable missiles.
Last month, Liwa al-Islam - one of the groups operating outside the Free Syrian Army - published a video purporting to show it operating the most sophisticated rebel anti-aircraft weaponry yet. The footage appeared to show the interior of a 9K33 Osa surface-to-air missile battery apparently captured from the government.
"A lot of this is about propaganda," said Afshon Ostovar, Middle East analyst at the Centre for Naval Analyses near Washington DC. "We don't know if they know how to use it. We don't even know if they have the missiles."
(Reporting by Peter Apps; Editing by Will Waterman)