KABUL, Afghanistan – A suicide bomber struck at the heart of NATO’s operation in Kabul on Saturday, killing at least six Afghan civilians in an attack that officials blamed on the Haqqani network — a militant group the U.S. has designated a terrorist organization.

The blast, just outside the sprawling headquarters of the U.S.-led military coalition, came as a senior Haqqani commander interviewed by The Associated Press vowed revenge for Washington’s decision.

The Obama administration gave the Pakistan-based Haqqani network, which is linked to the Taliban, a terrorist label on Friday despite misgivings the move could further stall planned Afghan peace talks.

The commander said the Haqqani network’s military commander, Sirajuddin Haqqani, wants to carry out “80 to 100 attacks on U.S. forces in Afghanistan and 20 attacks on other NATO members” in retaliation for the terrorist declaration.

The insurgents’ continued ability to strike so close to NATO headquarters has undermined coalition claims of improving security as foreign troops withdraw and hand over security responsibilities to Afghan forces by the end of 2014.

The heavily fortified Afghan capital has experienced a series of attacks that are particularly valuable because they score propaganda points for the insurgents by throwing doubt on the government’s ability to provide security in its seat of power.

The bomber, whom Kabul police estimated to be about 14 years old, struck just before noon on a street that connects the alliance headquarters to the nearby U.S. and Italian embassies, a large U.S. military base and the Afghan Defense Ministry.

He detonated his explosives while walking down the street, according to Kabul police. The Ministry of Interior said some of the victims were street children.

The blast occurred just a few hours after hundreds of Afghans and officials had gathered a few hundred yards away to lay wreaths at a statue to commemorate the 11th anniversary of the death of Ahmad Shah Massoud.

The charismatic Northern Alliance commander was killed in an al-Qaida suicide bombing two days before the Sept. 11, 2001, terrorist attacks in the U.S. The alliance joined with the U.S. to help rout the Taliban after America invaded Afghanistan a month later.

Interior Ministry spokesman Sediq Sediqi blamed Saturday’s attack on the Haqqani network, one of the most dangerous militant groups fighting international troops in Afghanistan. The Haqqani group has been responsible for several other high-profile attacks in the capital.

However, the Taliban claimed responsibility for the attack, saying the target was a “clandestine CIA-run headquarters” nearby. Taliban spokesman Zabiullah Mujahid said the explosion was carried out by a 28-year-old fighter from Logar province, south of Kabul.

The Haqqani commander, who spoke to The Associated Press on condition of anonymity because he feared being targeted if identified, also said the Taliban were responsible for the attack.

The terrorist designation bans Americans from doing business with members of the Haqqani group and blocks any assets it holds in the U.S. American officials estimate the Haqqani forces at 2,000 to 4,000 fighters and say the group, which is based in Pakistan, maintains close ties with al-Qaida.