Kabul ? A Taliban suicide bomber attacked officials leaving a mosque east of the capital Wednesday, killing the country’s deputy intelligence chief and 22 other people in a major blow to Afghanistan’s security forces.

The brazen assault occurred as tensions are running high after last month’s divisive presidential election and a sharp rise in U.S. casualties — events that have already raised alarm in Washington over the future of President Barack Obama’s strategy to turn the tide of the war.

A Taliban spokesman, Zabiullah Mujahid, claimed responsibility for the bombing, which happened as Afghan dignitaries were leaving the main mosque in Mehterlam, 60 miles east of Kabul, after ceremonies marking the Islamic holy month of Ramadan.

The bomber approached the crowd on foot and detonated an explosive belt, killing 23 people, including Abdullah Laghmani, deputy chief of Afghanistan’s National Directorate for Security and the target of the attack, according to provincial spokesman Sayed Ahmad Safi.