US secretary of defense Leon Panetta told reporters late on Thursday that intelligence indicates there is an "al-Qaeda presence in Syria."
"Frankly we need to continue to do everything we can to determine what kind of influence they're trying to exert there," Panetta said.
His remarks came after twin bombings in Damascus targeting a building used by Syria's pervasive secret police killed 55 and wounded 372.
The embattled regime of Syrian president Bashar al-Assad vowed after the attacks to continue its campaign against "foreign terrorists" in the country.
Assad's has described his brutal 14-month crackdown on the ongoing popular uprising against his regime as his own "war on terror."
However, his forces have exclusively targeted domestic dissidents - and in recent months rebels - who have risen up against his 11-year autocratic rule.
Assad has also sought to brand the rebel Syria Free Army as "foreign terrorists" and blamed them for the bombings targeting his government.
SFA rebels are predominantly Syrian army defectors commanded by dissident Syrian officers who sought refuge in Turkey.
Observers note the SFA is poorly organized and equipped, and does not have the infrastructure or technical base to carry out timed precision bombings. Instead, they have focused on lethal guerilla-style hit-and-run raids and ambushes.
The use of precision coordinated bombings like those in Damascus is a trademark of Al-Qaeda that emerged in Iraq and Afghanistan, lending some credence to Panetta's belief al-Qaeda is operating in Syria.
However, politicians in neighboring Arab states and Syrian dissidents have charged the Assad regime is targeting itself in order to present itself as a victim - and that the bombings could serve as a pretext for scuttling the tenuous UN-backed peace plan Damascus has agreed to.
Susan Rice, the US ambassador to the United Nations, said after the bombings on Thursday that it was to early to declare the UN-backed six-point peace plan brokered by UN special envoy Kofi Annan a "failure."
"Although we've been skeptical of the Syrian government's readiness and willingness to implement its commitments, what Annan is trying to do makes eminent sense and we support it," she said.
However, the April 12 ceasefire date is now a month past-due and has yet to be honored by the Assad regime, or the SFA – with rights activists saying at least 800 have been killed since the deadline passed.
Assad's forces have reportedly staged deadly raids on dissident neighborhoods almost immediately after UN observers tasked with enforcing ceasefire depart. There have also been reports of war crimes by Syrian troops in recent months, including the kidnapping, rape, torture, and summary execution of dissidents, rebels, and their families.
At present, there are 50 out of a slated 300 observers in Syria, leaving the force woefully under strength in a nation of 22.5 million spread over 71,479 square miles of disparate terrain.
UN officials place the death toll in Assad's brutal crackdown at "more than 9,000," but admit they stopped counting months ago due to the chaotic situation on the ground.
Independent rights groups place the death toll at almost 12,000 – most of them civilians.