U.S. says "sophisticated weaponry" hit chopper in Iraq

BAGHDAD (Reuters) - A transport helicopter that crashed in Iraq last week, killing all seven on board, was brought down by a "sophisticated piece of weaponry", the U.S. military said on Wednesday.

The Ch-46 Sea Knight, the Marine version of the twin-rotor Chinook, crashed near Baghdad on February 7, the seventh helicopter to be shot down in Iraq since January 20. The military initially said mechanical failure was probably to blame.

The high number of U.S. helicopters lost in less than a month has raised questions about whether insurgents in Iraq are using new tactics, such as studying aircraft flight patterns, or have acquired sophisticated weaponry.

Five of the downed helicopters were U.S. military aircraft and two belonged to a private American security company.

U.S. military officials have previously said they did not believe advanced missile systems were used in any of the attacks, which killed 28 personnel, and have referred only to machinegun fire bringing down the helicopters.

"It was probably brought down by some sophisticated piece of weaponry," the chief U.S. military spokesman in Iraq, Major- General William Caldwell, said of the downing of the Sea Knight.

He was speaking during a news briefing that concentrated on U.S. claims that Iranian-manufactured weapons are being used to kill U.S. troops in Iraq, but he insisted he was "not making any inferences" about where the weaponry had come from.

MISSILE

At a briefing on Sunday, U.S. military officials showed journalists an Iranian-made shouldered-fired missile.

Caldwell did not explain what he meant by "sophisticated weaponry", but an al Qaeda-backed group claiming responsibility for downing the aircraft, posted a video on the Internet showing an apparent missile hitting a twin-rotor helicopter that was then engulfed in flames and plummeted to the ground.

The U.S. military has said it does not believe the helicopter shown in the video was the Sea Knight.

The military, which relies heavily on helicopters to transport troops and equipment to avoid Iraq's dangerous roads, has said it is adjusting its tactics in the wake of the downings.

U.S. Major-General James Simmons said on Sunday U.S. helicopters were shot at on average about 100 times a month, the vast majority from small arms and automatic weapons fire. On average about 17 aircraft were hit a month, causing mostly minor damage.

Simmons said most of those were attacked while supporting ground forces or happened upon insurgents. But at least two of the seven helicopters downed since January 20 appeared to have been deliberately targeted.

In both cases the road to the crash site had been mined with roadside bombs and the helicopters had been engaged by what he called "multiple weapons systems".

"We are engaged with a thinking enemy. This enemy understands ... we are in the process of executing the prime minister's plan for the security of Baghdad. They understand the strategic implications of shooting down an aircraft," he said.

He said insurgents had used shoulder-fired missile systems against U.S. helicopters in the past to great effect. He said 29 U.S. Army helicopters had been shot down since 2003, a figure that did not include those used by the Marines.