The Russian military has been scrambling some US military drones performing in Syria, seriously disrupting American military operations, the channel NBC announced, citing anonymous US officials.

According to US officials, the Russians had started blocking some smaller US drones several weeks ago after a "series of alleged chemical weapons attacks on civilians in Eastern Ghouta." The NBC network’s sources stated that the Russian military was concerned that the US military would take revenge for the attacks and began jamming the GPS systems of the drones operating in the area.

"GPS receivers in most drones can be fairly easily jammed," Dr. Todd Humphreys, the director of the Radionavigation Laboratory at the University of Texas at Austin said.

The Defense Department cannot with certainty state whether the jamming is the cause of the drones crashing, according to the operational security.

"The US military maintains sufficient countermeasures and protections to ensure the safety of our manned and unmanned aircraft, our forces and the missions they support," said Pentagon spokesman Eric Pahon.

Deputy Chairman of the Russian Federation Council Committee on Defense and Security Yevgeny Serebrennikov has denied reports that Russia has blocked signals of US drones in Syria.

"This is more fake information from American media, which appears so often in recent times. Russia has repeatedly said that its actions, including in Syria, are made only in accordance with international treaties, such actions could not really have taken place," Serebrennikov said.

READ MORE: Reports of ‘Chemical Attacks' in Syria Used to ‘Justify External Intervention'

US-Russia Standoff

The announcement has been made following an alleged chemical weapons attack in Syria's Douma, a number of countries, including the US, jumped at the chance to blame Damascus for the incident.

Last week, the US Treasury Department added another 38 Russian entrepreneurs, senior officials and companies to its sanctions list in response to Russia's alleged "malign activity" worldwide.