Top secret US spy plane seen circling Russia amid growing World War 3 fears

A US surveillance plane has been spotted circling near Russia as tensions mount.

The aircraft, an RC-135U 'Combat Sent' plane, is equipped with high-tech communication equipment which allows it to communicate information directly with intelligence services.

It also has an in-flight refuelling system, allowing it to stay airborne for long periods of time as long as it can rendezvous with 'tanker' planes in the air.

One of the planes was recently seen circling over Kaliningrad, a Russian exclave between Lithuania and Poland. After flying over the territory, the jet returned to the UK, where it had taken off from RAF Mildenhall in Suffolk at around 2.32am.

The mission lasted for just over seven hours, with the plane arriving back at 9:36am, according to a flight record on FlightRadar24 (via The Daily Mail).

Its presence has drawn speculation as tensions continue to rise over Russia's invasion of Ukraine.

A 'Combat Sent' was spotted near Russia (US Air Force)

'Combat Sent' aircraft are used in strategic intelligence gathering, that is, information for long-term planning.

A description of the aircraft from the US Air Force describes it as 'locating and identifying foreign military land, naval and airborne radar signals,' and that it 'collects and minutely examines each system, providing strategic analysis for warfighters.'

In a war zone where the US is actively engaged, such intelligence may be used to direct other units, such as planes, drones, or even ground forces.

However, the purpose of the mission on October 7 over Russian territory is unclear.

The same aircraft, with the callsign JAKE37, was previously also shown making a similar run from the UK to Kaliningrad on October 2, with drones also spotted over Germany on the same day.

It comes as Russia's invasion of Ukraine continues to grind on, with Russia also seemingly probing into the airspace of other European countries.

In September, three Russian MiG-31 aircraft allegedly entered Estonian airspace for approximately 10 minutes.

Russian President Vladimir Putin (Contributor/Getty Images)

While Russia denied the violation, saying its planes were in neutral Baltic territory, Estonian Foreign Minister Margus Tsahkna said it was 'unprecedentedly brazen'.

Two weeks earlier, 20 Russian drones were detected passing over Ukraine before entering the airspace of NATO member Poland. Meanwhile, Romanian fighter jets also detected a Geran drone, a Russian variant of the Iranian-designed Shahed drone, in Romanian airspace.

At the time, NATO called the airspace violations 'increasingly irresponsible', warning Russia that it would defend itself using 'military and non-military' measures.

Under NATO's Article 5, member states are obligated to respond to an attack on any other NATO member as if it were an attack on them directly.

Ukraine's joining NATO has been a topic of discussion since before Russia's latest invasion, with Ukraine wanting membership while Russia is opposed.

The nature of Article 5 means that a ceasefire would be necessary for Ukraine to join; otherwise, it would participate while under attack, posing a difficult question about whether Article 5 would be triggered.

UNILAD has contacted the US Air Force for comment.