Afghanistan ? Insurgents launched a brazen pre-dawn assault today against the giant U.S.-run Bagram Air Field one day after a suicide bomber struck a U.S. convoy in the capital of Kabul, killing 18 people. The Kabul dead included five American troops and a Canadian and was 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 U.S. 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 U.S.-led mission.

A U.S. statement said seven insurgents had been killed so far during the “ongoing attack” on Bagram, which included rockets, small arms and grenades. Five service members have been wounded, the statement said without specifying whether they were Americans.

The Taliban claimed responsibility for the attack on Bagram, 30 miles north of Kabul. Taliban spokesman Zabiullah Mujahid said 20 suicide attackers carried out the attack.