A large U.S. military helicopter crashed yesterday while carrying up to 20 U.S. troops to reinforce a counter-terrorism mission in eastern...

KABUL, Afghanistan — A U.S. Chinook helicopter that crashed in eastern Afghanistan was likely shot down by hostile fire, and the fate of 17 U.S. service members aboard was unclear, the U.S. military said today.

The troops were on a mission against al-Qaida fighters in eastern Afghanistan when the helicopter went down yesterday in mountainous terrain near Asadabad, in Kunar province.

“The helicopter was transporting forces into the area as part of Operation Red Wing, which is part of the enduring fight to defeat al-Qaida militants,” a military statement said. “Initial reports indicate the crash may have been caused by hostile fire.”

Other helicopters and fixed-wing aircraft were sent to the crash site, the military said. Other details were not available, said U.S. military spokesman Lt. Col. Jerry O’Hara.

Provincial Gov. Asadullah Wafa earlier said the Taliban downed the Chinook CH-47 helicopter with a rocket. He gave no details.

Purported Taliban spokesman Mullah Latif Hakimi telephoned The Associated Press before news of the crash was released and said the rebels shot the helicopter down.

He said the rebels filmed the attack and would release the video to the media. He also claimed rebels killed seven U.S. soldiers in an attack in the same area, though U.S. spokeswomen Lt. Cindy Moore said no such attack had been made on a U.S. convoy.

Hakimi often calls news organizations to claim responsibility for attacks on behalf of the Taliban. His information has sometimes proved false or exaggerated, and his tie to the group’s leadership is unclear. The incident, the first reported shooting down of a U.S. military aircraft in Afghanistan since the Taliban militia was driven from power in late 2001, underscored the continued danger to U.S. and Afghan troops from revived anti-government armed groups, especially the Taliban.

The crash was the second of a Chinook helicopter in Afghanistan this year. On April 6, 15 U.S. service members and three U.S. civilians were killed when their chopper went down in a sandstorm while returning to the main U.S. base at Bagram.

The U.S. military has launched operations in several areas along the border with Pakistan. Those offensives target remnants of al-Qaida and the hard-line Taliban movement, as well as foreign fighters using high mountain passes to cross the largely uncontrolled border from Pakistan.

Yesterday’s crash comes after three months of unprecedented fighting that has killed about 465 suspected insurgents, 29 U.S. troops, 43 Afghan police and soldiers, and 125 civilians.

The violence has left much of Afghanistan off-limits to aid workers and has reinforced concerns that the war is escalating into a conflict on the scale of that in Iraq.

There are 19,000 U.S. troops stationed in the country, mostly engaged in hunting down and killing Taliban and al-Qaida forces. There also are 10,000 troops from other foreign countries, including a U.N. peacekeeping force in the capital, Kabul.

Afghan and U.S. officials have predicted the situation will deteriorate in the lead-up to legislative elections in September, the next key step toward democracy after a quarter-century of war.

Earlier yesterday, roadside bombs killed five Afghan policemen in Kunar. One bomb exploded on a road near Asadabad, killing a district police chief and his two sons. Officials said seven police were also wounded. Several rockets also landed near a U.N.-Afghan election commission office in Asadabad, causing no casualties.