The missiles that killed Qaeda boss Ayman al-Zawahiri were likely a secret variant that uses sharp blades, not explosives, to take out targets

• The missiles that killed Al Qaeda's leader were likely a secret variant, per media reports.
• Little is known about the Hellfire R9X missile, which is designed to kill without explosives.

The two Hellfire missiles that killed the leader of Al Qaeda in a drone strike last weekend were likely a secretive variant that deploys blades instead of explosive warheads to minimize civilian casualties.

The Department of Defense said that Ayman al-Zawahiri, who helped plan the 9/11 attacks, was killed by two Hellfire missiles in a safehouse at 6:18 a.m. on Sunday. Officials described the killing as a "precision, counterterrorism operation."

The Egypt-born al-Zawahiri was hiding in downtown Kabul with his family, President Joe Biden said in a Monday speech, adding that no civilians or family members had been killed.

A senior administration official said in the Department of Defense's statement: "We are confident through our intelligence sources and methods — including multiple streams of intelligence — that we killed Zawahiri and no other individuals."

Online photos of the building in which al-Zawahiri was housed showed its windows smashed but its structure intact — suggesting that no powerful explosion had taken place.

US authorities have not confirmed what type of Hellfire missiles was deployed in the operation. However, multiple media reports said it's likely that the Hellfire R9X variant was used because of the minimal collateral damage caused, citing defense experts and social media images of the aftermath.

According to open-source intelligence organization Bellingcat, the R9X is an air-to-ground missile that destroys its targets using its kinetic energy and six blades, which deploy just seconds before impact.

Much about the missile variant is shrouded in secrecy and there are no available public images of what it looks like before it's been fired.

The lack of explosives in the R9X reduces its area of effect, making it effective at killing individual targets while reducing the chances of civilian fatalities, per Bellingcat.

The R9X is suspected to have been used in the 2017 US assassination of Abu al-Khayr al-Masri, Qaeda's deputy leader, in Syria. Images on social media showed that the roof of al-Masri's car was shredded open on the passenger's side but that the engine suffered no damage, according to CBS.

Another attack in which the R9X may have been used was a 2020 US drone strike in Syria that killed three men, per Bellingcat.

Photos that circulated online in the aftermath showed a truck with a hole punched in its roof. The driver's cab was destroyed but the rear of the vehicle seemed relatively unscathed.

Bellingcat said the blades of the R9X appear to fragment on impact, which could explain why no completed blades have been found at attack sites.

Sunday's precision strike came nearly a year after the US mistakenly targeted an aid worker in Kabul with a drone strike, thinking he was an ISIS-K militant. The August 29 attack used a 20-pound Hellfire missile variant that killed 10 people, including seven children.