The White House announced Thursday evening the U.S. would ramp up its involvement in Syria' s civil war, but it remains unclear what actions Washington will take next.

In a conference call with reporters, White House officials announced a U.S. investigation confirmed the use of chemical weapons by Syrian government forces, crossing the "red line" that President Barack Obama drew last year that he said would spark U.S. involvement.

But the Obama administration has so far been vague on what exactly it aims to provide to rebels in war-ravaged Syria, and the White House said the president would discuss the issue with European allies at next week's G8 summit in Northern Ireland.

Wayne White, former deputy director of the State Department's Middle East Intelligence Office, told Xinhua the most obvious and less risky course of U.S. action would be to resupply large quantities of various small-arms or shoulder-fired anti-tank weapons to rebel forces that have been "vetted" as not adhering to radical ideology.

Such a move, if taken, would involve training in Turkey and Jordan in the use of those weapons, said White, now a scholar at the Middle East Institute.

The Obama administration could also decide to provide limited quantities of SA 7 weapons systems to those rebel factions the U.S. has vetted, to see if they can be trusted not to share the weaponry with extremist fighters, he said.

A big problem, however, is that the most successful rebel units are militants, White noted, and separating them from secular rebels could prove a difficult task.

"Even determining by engaging opposition leaders outside Syria precisely what rebel combatants inside the country genuinely do not have extremist leanings may not be entirely reliable," White said.

He added that monitoring forces using U.S.-supplied SA-7's inside the country would be a daunting challenge for U.S. or other foreign intelligence agencies.

Moreover, supplying only moderates leaves the most successful units undersupplied, he said.

White said it may not be too late for the U.S. to take action, but it could be difficult to do so in time to prevent additional gains for Syria's government over the next couple of weeks.

Syrian President Bashar al-Assad's Hezbollah allies already have largely deployed and are well-supplied, and Assad's forces have rebounded in part because of rising fears of what might lie ahead after a militant victory in the embattled country, White said.

"For now, much of the game (for the U.S.) may well be to get enough aid to the rebels fast enough just to contain government forces," he said.

But despite the White House's announcement that Syria's government crossed the "red line," Washington is in no hurry to ratchet up its involvement in the embattled country, some experts said.

"The United States will continue watching the battle closely, but not with an eye toward throwing itself into the fray," global intelligence company Stratfor wrote on its website Friday.

"The United States' strategic interest is to avoid becoming drawn further into another age-old sectarian vendetta that saps the United States' ability to maintain its balance in the world," the company contended.