Iran’s Revolutionary Guards Corps has ordered all of its members to stop using any type of communication devices after thousands of pagers and walkie-talkies used by its Hezbollah allies in Lebanon blew up last week, Reuters reported Monday.

An Iranian security official who spoke to the outlet said that a large-scale operation is underway by the IRGC to inspect all devices, not just communication equipment.

Most of the devices were either home made or imported from China and Russia, he said.

The official, who declined to be identified, added that Tehran was concerned about infiltration by Israeli agents, including Iranians on Israel’s payroll.

A thorough investigation of personnel has already begun, targeting mid and high-ranking members of the IRGC, the official said.

“This includes scrutiny of their bank accounts both in Iran and abroad, as well as their travel history and that of their families,” he continued.

Thousands of pagers exploded on Tuesday across Hezbollah‘s strongholds, killing at least a dozen people, including a ten-year-old girl.

A day later, hundreds of Hezbollah walkie-talkies exploded. The attacks killed 39 people and injured more than 3,000.

Lebanon and Hezbollah say Israel was behind the attacks. Jerusalem has neither denied nor confirmed involvement.

The Iranian security official declined to give many details on how the IRGC force, comprising 190,000 personnel, are communicating. “For now, we are using end-to-end encryption in messaging systems,” he said.