The German and Swedish air forces scrambled NATO jets on Aug. 3 after two Russian jets were detected heading toward Latvian airspace over the Baltic Sea.
The German Air Force reported that the jets from NATO's Baltic air-policing mission identified two Russian Su-30s.
The Russian pilots "behaved uncooperatively but not aggressively," the German Air Force said.
According to the German news outlet Bild, two German Eurofighters and two Swedish planes intercepted the Russian Su-30s.
The Russian jets were involved in a training exercise, but the flight plan had not been communicated beforehand, a German Air Force spokesperson told Bild.
"The transponders were switched off, and the pilots did not respond to radio requests," according to Bild.
NATO aircraft were scrambled 11 times in mid-June to identify and escort Russian aircraft that had violated rules while flying in international airspace, Lithuania's LRT news agency reported.
Most of the Russian aircraft were reportedly flying with no flight plans and had their onboard transponders turned off.
Andrii Kharuk
