Six die in copter crash, Afghan war toll mounts

* Helicopter reported shot down by missile

* Western force now big enough to win - Mullen

* Obama talks of 'effective exit strategy'

By Peter Graff

KABUL, July 14 (Reuters) - Six Ukrainians supplying British troops in Afghanistan were killed in a helicopter crash on Tuesday and two U.S. Marines and an Italian soldier were killed in what could become the bloodiest month in the 8-year-old war.

Authorities in Moldova said the cargo helicopter, owned by an aviation firm there, was brought down by a missile. The Taliban also claimed to have shot down the chopper, a rare occurrence.

Western forces confirmed a helicopter had crashed bringing supplies to a British base at Sangin in Helmand Province and six foreigners were killed.

In Brussels, a NATO spokesman said the cause of the crash was under investigation but he could not confirm details of passengers on board.

A total of 43 foreign soldiers have already died this month as U.S. and British troops simultaneously launched the two biggest operations of the war to seize Helmand province, the Taliban's opium-producing heartland.

The highest death toll for Western forces in Afghanistan since 2001 is 46 for an entire month.

The mounting death toll among Western troops in Afghanistan is fulfilling commanders' predictions that the deployment of large-scale U.S. reinforcements would mean higher casualties.

U.S. President Barack Obama, who has identified the insurgencies in Afghanistan and Pakistan as the main threat to U.S. security, is presiding over an escalation strategy in which the number of U.S. troops will rise from 32,000 to 68,000 by the end of the year.

About 57,000 American troops are in place now, along with another 36,000 troops from Western allies. Commanders have said they expect a sharp spike in casualties as new troops move into areas held by fighters ahead of an Aug. 20 presidential election.

"UNDER-RESOURCED IN PREVIOUS YEARS"

U.S. Chairman of the Joint Chiefs of Staff Admiral Michael Mullen, who arrived in Afghanistan on Tuesday, told troops at Bagram air base that Obama's new strategy meant there would now be enough troops to win.

"While we have under-resourced this in previous years, we're very committed to getting the resources right now for this fight," he said. "I believe to the depths of my heart and soul that we can succeed here."

In Washington, Obama, after meeting Dutch Prime Minister Jan Peter Balkenende, said: "All of us want to see an effective exit strategy where increasingly the Afghan army, Afghan police, Afghan courts, Afghan government are taking more responsibility for their own security."

This month's dead include at least 15 British soldiers and nine U.S. Marines, from two forces mounting unprecedented operations to seize control of Helmand, Afghanistan's most violent region, half of which had been under militant control.

Helmand produces the bulk of the Afghan opium crop that supplies 90 percent of the world's heroin.

The 10,000 U.S. Marines dispatched by Obama to the province's southern half, launched Operation "Strike of the Sword" this month. The remaining similar-sized British-led task force has launched operation "Panther's Claw" to the north.

The two operations have sent thousands of troops into Taliban-held territory, advances by foreign troops on a scale unseen in Afghanistan since Soviet troops withdrew in 1989.

The British deaths this month caused shockwaves in Britain. Prime Minister Gordon Brown, under fire for denying commanders' requests to send more troops, dispatched an extra company of 140 infantry soldiers to join the 9,000 strong force in the country.

The two Marines were killed in Helmand on Monday, U.S. forces spokeswoman Captain Elizabeth Matthias said, giving no further details.

Since the launch of the U.S. and British Helmand assaults, the Taliban have also stepped up raids in other regions. One Italian soldier was killed and three others wounded by a roadside bomb in the west of the country, the Italian military said. (Additional reporting by Andrew Gray in Bagram; Sayed Salahuddin, Jonathon Burch and Hamid Shalizi in Kabul and Ismail Sameem in Kandahar; Editing by Richard Balmforth)