Russia says it has spotted 21 foreign spy jets flying close to its borders for surveillance purposes over the past week.
A report published Friday in the Russian military’s official newspaper, Krasnaya Zvezda, showed that Moscow had to send fighter jets on five different occasions to prevent the spying jets from entering the country’s airspace.
None of the flights trespassed into Russian territories, the report added.
The United States and the NATO military alliance are known to have regularly flown aircraft equipped with strong radars and equipment to snoop on Russian military communications.
In January the Russian Defense Ministry announced that it had sent a Su-27 jet to intercept a US Navy EP-3 Aries surveillance plane near Russian territories over the Black Sea.
Russia carried out another interception in May, sending a Su-27 jet within 20 feet of a US Navy P-8 Poseidon spy plane flying off Russian coast.
The Pentagon slammed the interception as "unsafe," but Moscow replied that they took "all necessary precautions" to avoid a hazardous situation.
NATO has been increasing its presence on Russia’s borders over the past years, amassing weapons and equipment in the Baltic region.
The alliance’s expansion has intensified tensions between the two sides, resulting in numerous instances of military standoffs.
NATO aircraft often fly close to Russia’s borders as part of the so-called aerial policing missions, which the alliance says are designed to defend ill-equipped Baltic States – Lithuania, Estonia and Latvia – against the “Russian aggression.”