WASHINGTON — The brazen assaults on two prisons in Iraq this week were significant not only for the hundreds of prisoners who were freed but also for what they indicate about the growing capabilities of Al Qaeda’s Iraq affiliate, American officials and experts outside government said Tuesday.

The attacks on the prisons at Abu Ghraib and Taji were carefully synchronized operations in which members of the Qaeda affiliate used mortars to pin down Iraqi forces, employed suicide bombers to punch holes in their defenses and then sent an assault force to free the inmates, Western experts said.

“We are concerned about the increased tempo and sophistication of Al Qaeda operations in Iraq,” said a senior State Department official, who requested anonymity because he did not want to be seen as commenting on Iraq’s internal affairs.

James F. Jeffrey, who was the United States ambassador in Baghdad when the last American troops left in December 2011, said that Iraqi forces had performed poorly and that it was clear their skills had deteriorated now that the American troops training them were gone.