BAGRAM, Afghanistan (Reuters) - Suicide bombers carrying rockets and grenades launched a brazen predawn attack on one of the biggest NATO military bases in Afghanistan on Wednesday, killing an American contractor.
Nine U.S. troops were also wounded. About a dozen militants, many wearing suicide vests packed with explosives, were killed, the Pentagon said.
The fighting came the day after a suicide bomber attacked a military convoy in Kabul, killing 12 Afghan civilians and six foreign troops. The attacks may mark the start of a Taliban spring offensive against high-profile foreign targets.
The assault on Bagram air base, about an hour's drive north of Kabul and holding mainly U.S. troops, began in the predawn hours when about 30 Taliban insurgents attacked near the base's gates. It continued for hours with sporadic rocket and small arms fire.
A spokesman with the NATO-led International Security Assistance Force (ISAF) would not disclose the name or profession of the American contractor who was killed until the man's family had been notified.
One rocket landed inside the base, causing minor damage, but no insurgents managed to get inside Bagram, ISAF said.
Helicopter gunships hovered above the base.
"We're always prepared to deal with attacks on our base, the response this morning was immediate," said Lieutenant Colonel Clarence Counts, a spokesman for the Bagram base.
The Taliban said four suicide bombers blew themselves up outside the base's gates and others managed to get inside, but the Islamist group often exaggerates its operations.
A U.S. defence official estimated that four militants had been wearing suicide vests but said they were all killed before managing to detonate the explosives.
Another spokesman for the base said "at no point did the insurgents breach the perimeter of the base."
BOOST FOR TALIBAN?
The attacks may boost the stature of the Taliban after the arrests of some senior leaders early this year in Pakistan, combined with a belated announcement for the spring offensive, had some saying the insurgents were on the defensive.
The Taliban have announced an offensive from May 20 against the government, foreign forces and diplomats in Afghanistan in response to NATO plans for an operation against the group's southern stronghold of Kandahar.
"The Taliban are trying to show their reaction to the expected plan of NATO's operation in Kandahar in coming weeks," said Noor Ul-Haq Ulomi, a former general during the communist regime of the 1980s.
"(They) want to show ahead of it that they are strong as before and even getting stronger ... They want to show that with their small groups they are able to conduct organised attacks on NATO forces in Kabul and on their base in Bagram."
The Pentagon said it was too soon to speculate about the implications of this week's attacks. "The facts are what they are: there have been two events in two days. It would be premature to draw any sort of conclusion based on these two events," Pentagon spokesman Bryan Whitman said.
Bagram is the main base for the U.S.-led troops in Afghanistan, with the largest airfield in the country. It was used by the former Soviet Union during its invasion of Afghanistan in the 1980s.
Since it was taken over by U.S. troops, it has also housed a prison for Afghans detained by American forces. The centre has sewn resentment among Afghans because of reports of torture and ill-treatment of suspected Taliban prisoners.
"It was 3.30 in the morning when I heard gunshots and four explosions," said Mohammad Najib, who lives close to the base. "Minutes later two helicopters were firing heavily into orchards around the base."
There are regular roadside bomb attacks against foreign troops in Taliban strongholds in the south, but high-profile attacks like the Bagram and Kabul assaults are rarer.
The capital of four million people is heavily guarded with dozens of checkpoints manned by Afghan forces, who took over responsibility for the city's security more than a year ago.
Removed from power by U.S.-backed forces in 2001, the Taliban have made a comeback in recent years despite the growing number of foreign troops, now standing at some 140,000.
Thousands more U.S. troops are arriving as part of President Barack Obama's strategy to turn the tide against the militants.