KABUL, Afghanistan — The Afghan Defense Ministry went into a near-total lockdown Tuesday after the discovery of 10 suicide vests and the arrest of more than a dozen Afghan soldiers suspected of plotting to attack the ministry and blow up commuter buses for government employees, Afghan and Western officials said.
The security breach took place in one of the most fortified parts of Kabul, less than a mile from the presidential palace and the headquarters of the US-led coalition.
It raised the prospect that the Taliban, which committed a series of high-profile attacks inside Kabul last year, planned to pick up where it left off as winter snows give way to spring, clearing the high mountain passes and opening the annual fighting season.
Compounding the fears of renewed violence in Kabul was what appeared to be complicity of Afghan soldiers in the plot. Afghan soldiers and police officers have been killing their colleagues among the international military force here at an alarming rate in recent months — only hidden bombs have killed more coalition service members this year.
The killings have already reached into the heart of the Afghan security establishment; in February, amid riots over US soldiers burning Korans, an Afghan Interior Ministry employee shot dead two US military advisers in a restricted-access area of the ministry.
Three other coalition service members were killed Monday by Afghan security forces in two separate episodes in the country’s south and east.
The attacks by Afghan soldiers and police attacks on coalition forces have called into question a pillar of the United States’ exit strategy: the readying of the Afghan security forces to fight on their own. Now, in light of the potential plot against the Defense Ministry, it appears that elements of the security forces may also pose a threat to their own government.
Details of the latest plot, which officials said was uncovered Monday, remained sketchy, leaving unanswered questions about how the plotters gained access to the grounds of the ministry, which lie behind multiple checkpoints.
The Defense Ministry refused to even allow that a breach had occurred; it denied any attempted bombings and said no soldiers had been arrested.
But the denials were contradicted by a half-dozen Afghan and Western officials. While some praised Afghan security forces managing to stop the attack, all spoke on the condition of anonymity to avoid contradicting the Afghan government.
One Western official said at least 10 suicide vests were discovered in and around the ministry Monday afternoon. Most were found in guard sheds around a parking lot, and the belief among Afghan and Western officials is that the plan was to blow up buses carrying ministry employees home, the official said.
An Afghan army officer who handles administrative matters at the ministry gave a similar account.
“You have to be cautious when you come here. It is not safe here,’’ the officer said. The plotters “have links inside the ministry. Otherwise, they could not enter such a highly secured place.’’
Along with the usual contingent of Afghan army guards, special army commandos could also be seen protecting the Defense Ministry on Tuesday afternoon as the restrictions on movement in and out of the ministry began to ease.
A sergeant who was guarding the ministry said he and his men had been told by their superiors that the bombers might have been planning to enter the ministry and possibly the headquarters of the intelligence agency.
The sergeant said that two bombers might still be at large, thus the morning lockdown at the ministry and orders to search everyone trying to enter. He said that uniformed soldiers ordinarily walk into the ministry without being searched, an indication of a security weakness the plotters sought to exploit.
The Western official said a number of people, including Afghan soldiers, were arrested in connection with the plot Monday and Tuesday, but the official could not provide an exact figure.
Multiple Afghan television stations reported 10 arrests Tuesday and six Monday, although it was not clear whether the suspects were soldiers or civilians.
The security alert extended beyond the ministry. A fortified street that features the Canadian Embassy and the back entrance to the British Embassy along with compounds housing other international institutions was locked down briefly around noon.
No cars or people were allowed in or out of the checkpoints that control access to the street for about an hour, and Afghan security forces were a heavier-than-usual presence around a major traffic circle at one end of the street.
The Taliban has usually claimed responsibility for significant attacks on the capital. But Zabiullah Mujahid, a spokesman for the insurgents, said he was unaware of any attempt to attack the Defense Ministry.