KABUL, Afghanistan - A ruthless new generation of Afghan insurgents is casting aside Taliban doctrine that opposed killing large numbers of civilians, instead using more powerful explosives and packing bombs with ball bearings to maximize fatalities.
Just this week, some 140 people died in two bombings. Afghan security officials say the militants have started using C-4, a powerful explosive rarely seen before in Afghanistan.
"It's not like Baghdad, but the terrorists are learning lessons from each other," said Abdul Manan Farahi, counterterrorism chief for the Interior Ministry.
The recent bombings are part of a bloody trend in the deepening Afghan conflict. Militants have stepped up attacks, and NATO has boosted its forces and taken the fight to the Taliban. Last year was the deadliest since the US invasion of Afghanistan, with more than 6,500 people, mostly Taliban fighters, killed in militant-related violence.
Both sides have caused civilian deaths. According to an Associated Press count based on figures from Afghan and Western officials, militants killed 480 civilians in 2007, while US or NATO action killed 360 civilians - many of them in air strikes.
The United States and NATO have successfully worked to reduce civilian deaths since a spate of casualties in June drew stern warnings from President Hamid Karzai and outraged the Afghan public.
At the same time, a surge in suicide attacks in the past two years is increasingly putting Afghan civilians in the line of fire. There were six suicide bombings in Afghanistan in all of 2003 and 2004. Militants ramped up such attacks in late 2005 and they have been rising steadily since, culminating in more than 140 in 2007.
Sunday saw the deadliest insurgent bombing since the Taliban's ouster from power in 2001, when a suicide attack killed more than 100 people at a dog fighting match near the southern city of Kandahar. The next day, 38 Afghan civilians were killed when a suicide car bomber attacked a Canadian military convoy, officials said.
A Taliban spokesman claimed responsibility for Monday's attack, asserting that only police and soldiers were killed. But the spokesman denied the militia was behind Sunday's killings.
The Afghan government has not formally accused the Taliban of Sunday's attack. But Karzai's spokesman said the bombing had "all the hallmarks of previous attacks."
The Taliban insists it is avoiding attacks that target civilians.
But a militant spokesman said Taliban leaders have called on bomb-makers to raise the power of blasts against US and NATO military forces, which could increase the possibility that civilians will also be killed.
Reclusive Taliban leader Mullah Omar has in the past called on his fighters not to carry out attacks around civilians, apparently aware that such killings hurts the militia's cause. But a new breed of ruthless militants has replaced dozens of insurgent leaders who have been killed or captured.
A recent analysis by NATO theorized that while the older Taliban leadership associated with Mullah Omar sought to avoid civilian casualties, "the new guys just don't care," said an official at NATO's headquarters in Kabul who asked not to be identified when revealing internal reports.
The influence of one such commander, Siraj Haqqani, is growing, the US says. Haqqani, a Taliban-associated militant with close ties to Al Qaeda, is accused of coordinating beheadings and suicide bombings reminiscent of the deadliest days of the Iraq war.