Insurgents launched a brazen pre-dawn assault today against the giant US-run Bagram Air Field, the second Taliban strike at Nato forces in and around the capital in as many days.
At least 10 insurgents were killed so far in the "ongoing attack" on Bagram, which started at about 3am with rockets, small arms and grenades fired into the base, said Major Virginia McCabe, a spokeswoman for US forces at Bagram.
Seven US service members were wounded, she said.
The attack came one day after a suicide bomber struck a US convoy in the capital of Kabul, killing 18 people. The dead included five American troops and a Canadian, making it the deadliest attack on Nato in the Afghan capital in eight months.
The back-to-back attacks appeared part of a Taliban offensive that the insurgents announced earlier this month - even as the US and its partners prepare for a major operation to restore order in the turbulent south.
The insurgent attacks against both the capital and a major American military installation show the militants are prepared to strike at the heart of the US-led mission.
The Taliban claimed responsibility for both the Kabul bombing and the attack at Bagram, 30 miles north of Kabul. Taliban spokesman Zabiullah Mujahid said 20 suicide attackers were involved.
A building was damaged in the attack but it was "not a mission-essential building," Maj McCabe said. She said that while they could still hear occasional small-arms fire around the base late in the morning, "it is becoming more and more sporadic".
An Afghan provincial police commander, General Abdul Rahman Sayedkhail, said the attack began when US guards spotted would-be attackers in a car just outside the Bagram base.
The Americans opened fire, triggering a gunbattle in which at least one militant triggered his suicide vest. Running gunbattles broke out as US troops hunted down the other attackers.
In February 2007, a suicide bombing killed more than 20 people at a Bagram security gate while Vice President Dick Cheney was inside the base. Mr Cheney was unhurt but the Taliban said he was the target.
The Bagram assault occurred following the deadliest day of the year for US forces in Afghanistan with seven Americans dead - including two who died in separate attacks in the south.
Twelve Afghan civilians also died in yesterday's blast - many of them on a public bus in rush-hour traffic along a major thoroughfare that runs by the ruins of a one-time royal palace and government ministries.
The attacks followed a Taliban announcement earlier this month of a spring offensive - Operation Al-Fatah or Victory - which would target Nato forces, foreign diplomats, contractors and Afghan government officials.
The announcement was made on the eve of Afghan president Hamid Karzai's visit to Washington and came as US, Nato and Afghan forces were gearing up for a major operation to secure Kandahar, the biggest city in the south and the former Taliban headquarters before they were ousted from power in the 2001 US-led invasion. US officials believe control of Kandahar is the key to stabilising the Taliban' southern heartland.
The last major assault in Kabul occurred on February 26 when suicide attackers struck at two residential hotels, killing six Indians and 10 Afghans.
Afghan authorities blamed the February attack on Lashkar-e-Taiba, the Pakistan-based militant group that India blames for the 2008 Mumbai terrorist attacks that killed 166 people. Police stepped up arrests following the assault and said they had caught a number of would-be suicide bombers.
Also today, Afghan and Nato aircraft continued the search for an Afghan commercial airliner which disappeared Monday on a flight from Kunduz to Kabul with 44 people on board, including three British citizens and an American. Air traffic controllers lost track of the Antonov-24, operated by Pamir Airways, when it was about 55 miles north of Kabul.