BAGHDAD -- The U.S. military said Sunday it does not believe a recent wave of deadly attacks in Baghdad reflects a trend toward an overall increase in violence.

Navy Rear Adm. Gregory Smith, the military spokesman, said a wave of horrific violence, including a single attack on Thursday that killed 68 people in Baghdad, must be placed in perspective.

You have to "look historically at what happened in the last year to put in perspective what has happened in one week or two weeks in Baghdad," Smith said.

Violence around Iraq has dropped by about 60 percent in the past nine months, due mostly to an influx of thousands of U.S. troops, a cease-fire called by Shiite cleric Muqtada al-Sadr and a decision by tens of thousands of Sunnis to join forces with the U.S.

"On any given day, al-Qaida in Iraq and other extremist groups are still very much disposed to handing out violence indiscriminately," Smith said, adding that "I wouldn't look at the last two weeks as an increase or trend" toward rising violence.

Thursday's attack occurred in Baghdad's predominantly Shiite Karradah neighborhood, one of the capital's most vibrant commercial districts and a stronghold for the country's most powerful Shiite political party, the Supreme Islamic Iraqi Council.

Despite the attack targeting Shiites, Smith noted that al-Sadr and the majority of his Mahdi army continue to abide by their cease-fire, choosing "path of political and nonviolent ways."

He also said Iran continues to play a destabilizing role in Iraq, despite promises by its government to help Iraq reach peace.

"It would appear that inside Iran there are still groups and elements" who are training, financing and supplying weapons to "criminal elements" inside Iraq," he said.

Iranian President Mahmoud Ahmadinejad, who made a landmark visit to Iraq last week, has denied the U.S. allegations and insisted that the U.S. presence is what fuels violence in Iraq and the Mideast region as a whole.