The biggest US-led ground offensive of the five-month Afghan war entered a second day yesterday with B-52 planes again bombing thousands of Taliban and al-Qaeda forces in mountain bunkers in east Afghanistan.
US warplanes dropped two recently developed "thermobaric" 907kg bombs, which create a high-pressure blast that drives air out of a cave and potentially suffocates those inside, US defense officials said.
Afghan troop reinforcements and US advisers, repelled by the diehard fighters in the opening assault on the snow-covered mountain caves, gathered near Gardez, capital of Paktian Province, about 150km east of the capital of Kabul, to prepare for a new attack.
The sound of B-52 bombing was heard in Gardez, 30km from the fighting and smoke hung over the high altitude battlefield.
At least three Afghan soldiers and one US serviceman have died so far and there have been a number of Afghan and American wounded in the fighting.
The American death, the second US serviceman killed by enemy fire in the war, came as up to 5,000 al-Qaeda and Taliban troops, many of them Arabs and other foreigners, fired rockets, mortars and artillery to beat back outnumbered Afghan troops.
Afghan soldiers just back from the front said some US advisers, believed to number about 60 in all, were forced to abandon two four-wheel drive vehicles and flee for their lives.
The soldiers said the US advisers were extracted from the fighting at heights of at least 2,500m by US helicopters that braved intense fire to rescue them.
"Firefights have been intense at times in heavy combat actions. The exact size of the enemy forces occupying a series of cave complexes is not known," the US Central Command in Tampa Florida, which is in charge of the Afghan war, said in a statement.
Several days before the action started, US intelligence officials had estimated there were only 500 to 600 enemy fighters, but in light of the fierce resistance there was speculation this forecast was too low. Afghan soldiers said rather than the 500 to 600 al-Qaeda and Taliban fighters expected to be regrouping in the area, they ran into 3,000 to 5,000 fighters.
Afghan military officers and US advisers warned foreign journalists arriving in Gardez on Sunday to cover what may be the last major set-piece battle of the war to stay away from the front line.
"It is too dangerous," one US adviser said.
"It's a major operation, the biggest involving coalition troops of the war," said a US defense official in Washington, who asked not to be identified and declined to provide numbers.