US officials believe Russia may be behind the suspected directed-energy attacks that are getting government employees sick around the world, report says

• The US has been probing suspected directed-energy attacks on government employees, Politico reported.
• Sources told Politico that investigators were looking into Russia's GRU as a potential suspect.
• Victims reportedly have the same symptoms that US officials in Cuba and China experienced in 2016.

US officials believe that Russia may be behind the suspected directed-energy attacks on US government employees around the world, Politico's Lara Seligman and Andrew Desiderio reported.

Three current and former officials told Politico that US officials suspect the GRU, Russia's foreign intelligence agency. The report added, however, that the investigators do not have a smoking gun tying the suspected attacks to Russia.

A congressional official who was briefed on the issue told Politico that US officials had told lawmakers that the investigation into the suspected attacks was expanding, and that it was focused on whether the GRU was involved.

CIA Director William Burns is also receiving daily briefings on the investigation, Politico reported, citing two people familiar with the matter.

The suspected attacks have affected US personnel at embassies around the world, Politico reported.

Politico previously reported that officials were investigating a suspected attack on federal government personnel in Miami last year, as well two suspected attacks on National Security Council officials: One who was walking near the White House, and another in Virginia.

The victims have the symptoms of what has been dubbed the "Havana syndrome" - a mysterious set of unexplained symptoms that suddenly struck US officials in Cuba and China in 2016, Politico reported.

US and Canadian diplomats in Cuba started hearing strange sounds and reporting symptoms like nerve damage and headaches. Doctors said they were caused by mild traumatic brain injuries.

US officials in China and Russia have reported similar symptoms. Studies have pointed to microwave radiation as the main suspect.

A spokesperson for Director of National Intelligence Avril Haines told Politico that the US intelligence community has "no definitive information about the cause of these incidents" and has not concluded whether a foreign entity was responsible.