Taliban's spring offensive is a worrying sign

Afghan National Army soldiers hold rocket-propelled grenade launchers as they keep watch near the scene of an attack in Kabul on April 15, 2012. The capital came under coordinated attack Sunday, with explosions and gunfire rocking the diplomatic enclave as militants took over a hotel and tried to enter parliament.

(CBS News) The Taliban today claimed responsibility for a wave of attacks across Afghanistan that continue.

The insurgents say their strikes in Kabul and three other cities herald the beginning of a new spring offensive.

CBS News correspondent Allen Pizzey reports the co-coordinated attacks included both gunmen and suicide bombers.

Separate assaults in the capital targeted NATO bases, the Afghan parliament and several embassies, including the U.S. compound.

Afghan forces used assault rifles and rocket-propelled grenades to try to dislodge the handful of Taliban fighters who took positions in high buildings, and fought for more than seven hours.

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There were also attacks against NATO bases and government facilities in three other cities.

A Taliban spokesman said it was the start of the "spring offensive," and retaliation for U.S. troops burning Korans, urinating on bodies, and last month's killing of seventeen civilians by a lone Army sergeant.

The attackers managed to penetrate what is supposedly a "ring of steel" around the Afghan capital, put in place two years ago and also breached last September when Taliban fighters managed to hit the U.S. embassy.

An Afghan government minister blamed forces from what is known as the Haqqani network, an offshoot of the Taliban headquartered in Pakistan.

"One has to be concerned about seven simultaneous attacks countrywide. It does show a certain resilience by the adversary. In the end, there may very well be more casualties of insurgents than innocent civilians or government troops," said Michael O'Hanlon with the Brookings Institute.

In a written statement the international forces commander, U.S. General John Allen said he was "enormously proud" of the Afghan response: "They were on scene immediately, well-led and well-coordinated."

Sunday's gunfire echoed well into the night. The Taliban spokesman said the attacks had been planned for months and promised more there were more to come.