KABUL, Afghanistan — A Pakistani wore the vest rigged with explosives; a Kabul University medical student did the planning. And a soldier new to the Afghan Army — promised 25,000 Pakistan rupees, about $290, for his trouble — provided the vital military uniform that made possible the attack here Saturday on the grounds of the national military hospital.  Those were among the details released Monday as Afghan officials announced the arrests of 5 men, including the medical student and the soldier, accused of planning and carrying out the deadly suicide blast, which killed 6 people and wounded more than 20 others in a dining tent on the hospital grounds here.  Security officials, who said the men confessed, offered a chilling account of how the attack was orchestrated. Many of details were missing, including any sense of what drove the men to turn to the insurgency. Still, the account offers a rare glimpse inside the kinds of terrorist-style attacks that have become increasingly common as the war in Afghanistan grinds into its 10th year.  NATO officials, meanwhile, citing what they described as credible intelligence sources, said the Haqqani network, a Taliban ally based in the Pakistan tribal area of North Waziristan, was responsible for the attack.  In a spring offensive largely distinguished so far by suicide attacks and bombings, many observers said the attack on a hospital — even a military hospital — hit a new low. It was part of a pattern in recent months in which Afghan service members or insurgents dressed like them were able to infiltrate heavily guarded government compounds and carry out attacks inside.  The ringleader in Saturday’s attack was a 23-year-old medical student at Kabul University named Noor Agha, said Lutfullah Mashal, a spokesman for Afghanistan’s main intelligence service. Mr. Agha had joined the Taliban six months ago with the help of man known as Bashir. Officials gave no details about Bashir.  Another of the accused, a 19-year-old soldier named Akmal, who like many Afghans goes by one name, was assigned to the 53rd Health Battalion at the hospital, officials said. He joined the army eight months ago and completed training at the Kabul military training center. Two months ago he became friends with a man named Waris, who introduced him to insurgents. They gave him two vests for suicide bombing, officials said.  Then, two weeks ago, Waris returned from a trip to Pakistan and told him of a plan to attack the hospital. Mr. Akmal would play a pivotal role, providing the army uniform, a fake army identification card, and one of the vests to the bomber, who was to be brought in from Pakistan. In return, Waris promised him 25,000 rupees, Mr. Mashal said.  Officials did not say what roles the other three who had been arrested played in the attack, nor how the five met. All were from the Shakar Dara District of Kabul Province. The other three arrested were Said Agha, 27; Abdul Baseet, 19; and Khalis, 20, who goes by one name. Mr. Baseet and Mr. Khalis were madrasa students from the same village. Officials did not say what Mr. Agha did for a living.  Four days before the attack, officials said, the bomber arrived from Pakistan. His name was Faqir, and he had been trained to be a suicide bomber in the disputed Kashmir region of Pakistan and India, Mr. Agha, the medical student, told investigators. Faqir was turned over to Mr. Agha, Mr. Mashal said.  The morning of the attack, the men met in the bathroom of a mosque in downtown Kabul. Faqir put on the uniform and the explosive-laced vest, officials said. Then Mr. Akmal escorted him to the hospital, past a checkpoint to a dining tent on the grounds outside the main building. That is where Mr. Akmal left him, officials said, just as dozens of medical students and soldiers training to be combat medics were sitting down to lunch.
Two days after a deadly attack on a Kabul hospital, there are five arrests and some answers on how a suicide bomber got inside a heavily guarded area.