By Muhanad Mohammed
BAGHDAD (Reuters) - Iraq has launched a military crackdown on smuggling gangs, al Qaeda militants and Shi'ite militias responsible for recent attacks U.S. forces, security officials said on Sunday.
Triggered in part by a spate of attacks on U.S. forces last month, the crackdown aims to staunch the flow of illegal weapons into mainly Shi'ite southern Iraq from Shi'ite neighbor Iran.
In one of the largest offensives, about 3,000 Iraqi troops and police were mobilized against militias and smugglers in southern Maysan province, a provincial official said.
June was the deadliest month for U.S. forces in Iraq in three years, and Iraq's police and army have been under increased attack for months as a year-end deadline nears for the withdrawal of U.S. troops.
U.S. officials blame Iranian-backed Shi'ite militias for many of the attacks. Maysan shares a long border with Iran.
Major-General Qassim al-Moussawi, the spokesman for the Iraqi military's commander-in-chief, said security forces were arresting militants, searching for weapons caches and stepping up patrols to cut down on rocket and mortar fire on U.S. bases.
"We are implementing a tight security plan including all outlaw groups. Part of this plan is to control Iraq's border perfectly," Moussawi said.
"The entry of illegal arms to Iraq is contributing to undermining security, whether the weapons are used against U.S. or Iraqi troops, in assassination operations or armed robbery."
More than eight years after the U.S.-led invasion to oust Sunni dictator Saddam Hussein, the United States still has around 47,000 troops in Iraq. A full withdrawal is expected by year-end in accordance with a joint security pact.
While overall violence has steadily declined since the height of sectarian conflict in 2006-7, gun and bomb attacks still occur daily, often targeting Iraq's army and police.
Attacks against U.S. soldiers appear to be rising as Iraq's leaders discuss the divisive issue of whether to ask Washington to leave some troops beyond December.
Fourteen U.S. service members were killed in hostile incidents in June, the largest number since June 2008.
Security officials said the offensive is targeting criminal gangs and smugglers in addition to militants linked to Sunni Islamist al Qaeda and members of Shi'ite militias.
U.S. Defense Secretary Robert Gates, in a Reuters interview last week, said Iran was "absolutely complicit" in the growing U.S. casualties in Iraq.
James Jeffrey, the U.S. Ambassador to Iraq, said Iran's Islamic Revolutionary Guards Corps (IRGC) and its Qods force special operations unit were supplying "significantly more lethal weapons systems" to some Iraqi militias.
"Of particular concern, at least to me, is the Sadrist movement. The AAH (Asaib al-Haq) and the Kata'ib Hizballah are basically nothing more than thuggish clones of their IRGC Qods force masters," he told reporters in a briefing on Saturday.
Kata'ib Hizballah last month claimed responsibility for a rocket attack on a Baghdad base which killed six U.S. soldiers.
While southern Iraq has been relatively peaceful in recent years compared to restive central Diyala province and the city of Mosul, an al Qaeda stronghold in the north, Maysan is believed to be a key importation point for Iranian weapons.
Abbas al-Bayati, a member of the security and defense committee in parliament, said the crackdown was focused on central and southern provinces.
"The increasing death toll among Iraqis and U.S. troops in June is part of the (reason) for this security plan," he said.
A Maysan security official who asked not to be named said Shi'ite militias had protection from political parties in the past, but all the province's political blocs had agreed those involved in arms smuggling had to be hunted down.
"The goal of this operation basically is to prevent the infiltration of weapons which are used to attack U.S. troops and Iraqi security forces," the official said.
(Editing by Jim Loney; Editing by Jon Boyle)