By Mirwais Harooni and Emma Graham-Harrison
KABUL (Reuters) - An Afghan employee of the U.S. government opened fire inside a CIA office in Kabul on Sunday evening, killing an American and injuring a second, U.S. and Afghan officials said, in the second major breach of embassy security in two weeks.
The killing adds to a sense of insecurity already heightened by a 20 hour-siege of the diplomatic district in mid-September, and the assassination a week later of the top government peace envoy, former President Burhanuddin Rabbani.
The CIA compound inside the Ariana hotel is one of the most heavily guarded in Kabul, and has been off-limits -- along with the road that runs beside it -- for almost a decade, since shortly after the Taliban's fall from power in 2001.
It also lies at the heart of the capital's heavily guarded military, political and diplomatic district, a virtual "green zone" that is almost impossible for ordinary Afghans to enter.
It was not clear if the U.S. citizens were victims of a rogue employee who had been won over to the insurgent cause, or just the escalation of an argument in a city where tensions are high and many people carry guns. There are precedents for both.
The "lone attacker" was killed, and the injured U.S. citizen was taken to a military hospital, U.S. embassy spokesman Gavin Sundwall said on Monday.
"There was a shooting incident at an annex of the U.S. embassy in Kabul last night involving an Afghan employee who was killed. The motivation for the attack is still under investigation at this time," Sundwall said.
Sundwall declined comment on whether the annex housed the CIA, but Kabul Police Chief Ayub Salangi said there had been an exchange of fire at the Ariana hotel, which he described as a CIA office. He declined further comment on what happened in an area where access is restricted even for Afghan forces.
TURNED BY THE TALIBAN?
The shooting follows a string of attacks by Afghan security forces against their NATO-led mentors carried out either by "rogue" soldiers and police or by insurgents who have infiltrated security forces.
Taliban spokesman Zabihullah Mujahid could not immediately be reached for comment, but a senior Taliban commander reached by phone from Pakistan said the man had secretly joined the insurgents after a group of Taliban approached him to remind him "of his moral and religious duty as an Afghan."
"He used the enemy's weapons against the enemy and that's what we have been doing everywhere in Afghanistan," said the Taliban commander, who is operating in Afghanistan and asked for anonymity for security reasons.
"This place is at the heart of Kabul and we wanted to tell the Americans that we can chase them anywhere," he added.
The United States is investigating as one possibility that militants of the Haqqani network may be connected to the attack, a U.S. official said in Washington. It is also looking into whether the attacker acted entirely on his own on some personal grievance.
"An investigation into the incident is ongoing, and no further motivation for the attack are available at this time," the U.S. official told Reuters.
Officials in Washington did not question that it was a CIA office.
The Ariana hotel is just a few blocks away from the Presidential Palace and the U.S. embassy, and has been used by ruling regimes for many years.
Waheed Mujhda, of the Afghan Analytical and Advisory Centre in Kabul, questioned the Taliban's claim of responsibility and said the incident characterised the level of mistrust between the United States and its Afghan allies.
"This is a big security concern for the Americans and it shows they can't fully trust their Afghan staff. But the Americans never want to accept that there are serious trust and cooperation issues and they have encountered that in their security operations with Afghan forces."
HISTORY OF ATTACKS
The CIA suffered the second deadliest attack in its history on an Afghan base at the end of 2009, when a would-be informant blew himself up, killing seven CIA officers.
The agency has acknowledged "missteps" and "shortcomings" that included failing to act on warnings about the assailant from Jordanian intelligence or take security precautions.
Suicide bomber Humam Khalil Abu-Mulal al-Balawi tricked the CIA into believing he could be a useful tool in the battle against al Qaeda, and was invited inside a well-fortified U.S. compound in Khost province, near the border with Pakistan.
The CIA director at the time, Leon Panetta, made 23 changes after that attack, but noted that counterterrorism work still required working with "dangerous people in situations involving a high degree of ambiguity and risk."
Sunday's shooting came the same month that insurgents took over an unfinished high-rise near the city's heavily guarded military, political and diplomatic heart and showered rockets down on the U.S. embassy and NATO headquarters.
That attack lasted 20 hours, and the United States has blamed it on the Haqqani network of militants, who were long based in Pakistan's lawless frontier regions although they now say they have moved back into Afghanistan.
Washington accused Pakistan's spy service of offering them support. Pakistan has strongly denied the allegations.
(Additional reporting by Jibran Ahmad in Peshawar, Mark Hosenball in Washington and Martin Petty in Kabul; Editing by Jonathan Thatcher and Jackie Frank)