3:36 AM PDT, July 18, 2009

KABUL, Afghanistan — An American fighter jet crashed today in eastern Afghanistan, killing the two-man crew, U.S. military officials said.

The crash of the F-15E came amid what has already proven the deadliest month for Western troops in the course of the nearly 8-year-old Afghanistan conflict.

At least 50 coalition service members, including 26 Americans, have been killed so far in July. The highest previous monthly tally for Western troop fatalities in Afghanistan was 46.

American military officials have said the ongoing buildup of U.S. troops, together with a push into some previously insurgent-controlled areas, is likely to exact a rising casualty toll in coming months.

The forces of Britain and Canada, two crucial allies in the NATO coalition, have also seen a spike in fatalities this month, which has set off wrenching domestic debate in both countries about the effectiveness of Western war strategy in Afghanistan.

The cause of the jet's crash was being investigated, but military authorities said they have already ruled out the possibility that it was shot down.

"The crash was not due to hostile fire," U.S. forces in Afghanistan said in a statement.

Afghan officials in Ghazni province said American troops had sealed off the crash scene.

The fighter jet, known as a Strike Eagle, is a modified version of the supersonic F-15E. It is often used to provide "close air support" — that is, to hit ground targets during combat operations.

However, U.S. military officials said they were not aware of any clashes in Ghazni at the time of the crash, which occurred at about 3:15 a.m. local time.

The military did not disclose what the fighter jet's mission was, other than that it was "conducting coalition operations."

Insurgents in Afghanistan on rare occasions have been able to bring down helicopters, but there is no known instance of them shooting down a fighter plane. Even losses of such sophisticated craft due to weather or mechanical failure are rare.

A crash this week of a helicopter carrying private military contractors in Helmand province, in Afghanistan's south, is under investigation. All six of those aboard that chopper, identified as Ukrainian nationals, were killed.

The Moldovan contractor said the helicopter was shot down, and the Taliban claimed responsibility. Helmand this month has been the scene of a wide-ranging offensive spearheaded by U.S. and British forces.

Eastern Afghanistan, where the fighter jet crashed, has also been a trouble spot for much of the summer. It borders Pakistan's volatile tribal areas, where Pakistan's military has been carrying out off-and-on operations against the Taliban in recent weeks.

A concerted campaign of missile attacks by unmanned U.S. drones in the tribal areas has also targeted militant commanders linked to the Taliban and Al Qaeda. The Taliban use the tribal areas as a springboard for attacks on Western troops across the border in Afghanistan.

Earlier this month, a U.S. serviceman went missing from a base in eastern Afghanistan. The American military has said he was presumed captured, and the Taliban claim to be holding him.

- Laura.King@latimes.com