The Iraqi branch of al Qaida, seeking to exploit the bloody turmoil in Syria to reassert its potency, carried out two recent bombings in the Syrian capital, Damascus, and likely was behind suicide bombings Friday that killed at least 28 people in the largest city, Aleppo, U.S. officials told McClatchy.

The officials cited U.S. intelligence reports on the incidents, which appear to verify Syrian President Bashar Assad’s charges of al Qaida involvement in the 11-month uprising against his rule. The Syrian opposition has claimed that Assad’s regime, which has responded with massive force against the uprising, staged the bombings to discredit the pro-democracy movement calling for his ouster.

The international terrorist network’s presence in Syria also raises the possibility that Islamic extremists will try to hijack the uprising, which would seriously complicate efforts by the United States and its European and Arab partners to force Assad’s regime from power. On Friday, President Barack Obama repeated his call for Assad to step down, accusing his forces of “outrageous bloodshed.”…

“This was Zawahiri basically taking the shackles off,” said a U.S. official with access to the intelligence reports. Like others interviewed for this story, he spoke on condition of anonymity because the issue involves classified information.