Russia has been trying to find ways to interfere with the RQ-4 Global Hawk reconnaissance drones of the US Air Force (USAF), say US officials quoted by the portal. Defense Blog. 

In recent months, USAF drones have been increasingly active in Russia's western border regions, observing Russian bases in the Ukraine, Crimea and Black Sea regions. Moscow has been trying to jam signals from drones. 

According to the website, the Russians sent electronic warfare ground systems to the Crimea region, such as the Krasukha-4, R-330Zh Zhitel, R-330M1P Diabazol and Murmansk-BN, which can interfere with enemy radio frequency signals at distances of up to 5000 kilometers. 

A Beriev A-100, the Russian Air Force's newest airborne early warning aircraft, was deployed on April 21 (Wednesday) when a US Global Hawk flew over eastern Ukraine. Successor to the A-50 Mainstay, the A-100 is equipped with modern signals intelligence and electronic warfare sensors. 

Developed and manufactured by Northrop Grumman, the RQ-4 Global Hawks are unmanned high-altitude, long-endurance (HALE) aircraft used in intelligence, surveillance, and reconnaissance (ISR) missions. It is used by the US, South Korea and the NATO. Recently, the manufacturer made the First flight of a Japanese RQ-4.