Kabul, Afghanistan (CNN) -- As Afghan authorities announced the arrest of an alleged militant for planning last week's assault on Kabul, a bomber targeted a U.S. base outside the capital, the latest attempt by militants to strike the seat of Western and Afghan power.
The NATO-led command said the latest explosion occurred around 5 p.m. Tuesday outside the main gate at Camp Phoenix, a U.S. military base on the outskirts of the capital. It said initial reports indicate that the blast was caused by a vehicle bomb, but did not release any casualty figures.
The Taliban has claimed responsibility for the attack, authorities said.
An Afghan military official at the scene of the strike said the vehicle blast injured eight Afghan civilians and two U.S. service members, and an eyewitness showed CNN digital camera photos of about 11 or 12 injured people.
Taliban spokesman Zabullah Mujahid claimed in a text message that the strike killed 25 soldiers and damaged three tanks.
Afghan soldiers cordoned off the area about 60 meters, or more than 65 yards, from the blast.
The latest explosion erupted eight days after a dramatic and well-coordinated assault on key government sites in Kabul killed five people and wounded more than 70 others. The January 18 strike was particularly audacious because militants penetrated the Afghan government's power centers as members of Afghan President Hamid Karzai's Cabinet were to be sworn into office.
The National Directorate of Security on Tuesday announced the arrest of a 29-year-old man named Kamulddin in connection with the attack and released a video of him confessing to the coordinated strike.
In the video, Kamulddin said the plan was hatched in Pakistan by the Haqqani network, a militant group with ties to al Qaeda and the Taliban. An NDS spokesman confirmed the network ordered the assault and confirmed that the attack was planned outside of Afghanistan.
About 20 Taliban insurgents entered the presidential palace; the ministries of Finance, Mines and Justice; and the Serena Hotel, an Afghan government spokesman said. NATO-led forces said "several small explosions" and gunfire were reported near the Feroshgah-e-Afghan Shopping Center and the Serena Hotel, and later added that "numerous" suicide bombers had attacked government buildings close to the presidential palace and the Ministry of Justice.
Seized around 24 hours after the strike, Kamulddin said he sheltered suicide attackers in his Kabul house, and the men had weapons and explosive-laden vests. Along with the bombers, there were three or four attack coordinators, Kamulddin said in the video.
The Afghan Taliban initially claimed responsibility for the blast, but Kamulddin said the plan was organized in Pakistan by the Haqqani network, a group with cross-border ties to Taliban militants and believed to be behind a majority of the suicide attacks in the country. The network has a presence in southeastern Afghanistan and the Pakistani tribal region.
NDS spokesman Sayed Ansari also said the NDS arrested five people for their alleged roles in other attacks, including a September 2 bombing that killed Abdullah Abdullah Laghmani, the deputy head of the NDS.
Raids across Afghanistan late Monday and Tuesday led to the detention of insurgents, the discovery of weapons and the killing of at least one militant, according to releases from NATO's International Security Assistance Force.
ISAF forces killed "several armed insurgents "on Tuesday in Konar province, in eastern Afghanistan with an airstrike targeting insurgents seen "maneuvering to a fighting position previously used to stage attacks."
International forces have been bulking up their troop presence in recent months to counter militants. In the latest move, Chancellor Angela Merkel said Germany will send 500 more troops to Afghanistan to work in security and training. ISAF said that nation has more than 4,200 troops in the country.
--CNN's Atia Abawi and Tim Schwarz contributed to this report