BAQOUBA, Iraq (AP) – More than 700 additional American troops arrived in Iraq’s increasingly volatile Diyala province on Tuesday to try to quell burgeoning violence northeast of Baghdad during a security crackdown in the capital.

The Army’s 5th Battalion, 20th Infantry Regiment, 2nd Infantry Division moved from northern Baghdad into Baqouba early Tuesday to supplement about 3,500 American soldiers already stationed there.

The move comes at a time when more than 20,000 new American troops are pouring into Baghdad as part of a U.S.-Iraqi push to pacify the capital. The idea is to bring Baghdad’s violence down to a level that is manageable for Iraqi forces, in hopes that the fragile Iraqi government has room to function.

While sectarian killings in Baghdad have fallen since the crackdown began last month, violence has skyrocketed to the northeast in Diyala, where direct attacks on American forces have risen 70 percent since last summer, according to American military figures.

Major General Benjamin Mixon, commander of the Army’s 25th Infantry Division and the top American official in northern Iraq, said late Monday that the decision was not a last-minute reaction to an uptick in violence there.

“We began looking at this several months ago, in support of the Baghdad plan. We knew the surrounding provinces would be in play,” General Mixon told The Associated Press.

“I recognized for sure that Diyala would become more violent as operations picked up in Baghdad,” General Mixon said.

The additional American forces join more than 20,000 Iraqi security forces currently serving in Diyala, according to figures provided by the American military. About half of those are Iraqi police, and half are members of the Iraqi 5th Army Division.

“This should be fun, but three months and it’s over,” said Sergeant Todd Selge, 22, of Burnsville, Minn., whose unit is slated to leave Iraq in late spring. “We’ve heard that a lot of insurgents have moved here from Baghdad. The Iraqi Army is supposed to be OK here, so we’re coming to help them stand up.”

General David Petraeus, commander of all American forces in Iraq, said last week that it was “very likely there will be additional forces” going to Diyala.

“Baqouba is one of the sectarian fault lines, and in fact is an area of concern right now,” he told reporters Thursday in his first news conference since taking command last month.

With violence down in Baghdad, American troops will fan out to other communities on the rim of the capital to shut down factories rigging car bombs, which remain a threat despite a recent drop in execution-style killings in the city, the American military said Monday.

At least 55 people have been killed by bombs in Baghdad over the last three days, including two security guards who died Monday in a blast against an Agriculture Ministry convoy in the southeast of the city.

Chief American spokesman Major General William C. Caldwell said most of the car bombs and improvised explosive devices – the military’s term for roadside bombs – are believed to be rigged in makeshift factories in the towns along the edge of the capital.

“And that’s where the greater presence of these forces will go,” General Caldwell said without elaborating or giving a timeframe.

American officers have said Baghdad, a city of about 6 million people, cannot be made secure without extending the security operation into Sunni and Shiite communities that control major highways into the capital.

During a press conference, General Caldwell said American and Iraqi troops already had destroyed “two or three” car bomb factories since the Baghdad security operation began.

But that has not been enough to shut down the bombers.

On Sunday, an explosives-laden car rammed a flatbed truck packed with Shiite pilgrims returning from Karbala, killing 32 people in the mostly Shiite neighborhood of Karradah.

The day before, 20 people died in a car bombing about 300 yards from a joint U.S.-Iraqi security station in Sadr City, stronghold of the Mahdi Army of radical Shiite cleric Muqtada al-Sadr.

During a press conference, General Caldwell urged the public to be patient, saying only two of the five American Army brigades earmarked for the crackdown are operating in the city.

“But the build-up will continue through the spring time, and it will be late May before all the forces are here in the Baghdad area,” he said.

The security crackdown already has seen a decline in execution-style killings, random shootings and rocket attacks, in large part because Shiite parties have been successful in convincing the Shiite militias to pull armed fighters off the streets to avoid a showdown with the Americans.

Police found only nine bullet-riddled bodies in Baghdad on Monday – apparent victims of Sunni-Shiite reprisal killings. Before the security crackdown, the daily count was running above 50.

On Tuesday, a roadside bomb hit a minibus carrying Industry Ministry employees in northern Baghdad, killing two workers and wounding six.

And in Suwayrah, 25 miles south of Baghdad, police dragged two bodies out of Tigris River, a morgue official said in Kut. The bodies showed signs of torture.

Also in Kut, gunmen killed an interpreter working for coalition troops. Police said Ibrahim Sasa was killed in the center of the provincial capital.