A U.S. military heavy lift aircraft which flew into Moscow with its transponder on, allowing open-source tracking software to follow its progress, gained attention given the rarity of direct U.S. flights to Russia during the present period of strained diplomatic ties.

A U.S. Air Force C-17 Globemaster III flew from the capital of NATO-member Latvia to an airport near Moscow, Russia on Tuesday morning. The military jet first flew on Sunday from Andrews Air Force Base near Washington D.C., reports France’s Le Figaro, citing the open source transponder data which is collected by hobbyist ground-based receivers and aggregated through services such as the Flight Radar app.

Military flights are not obliged to keep their transponders on, but it is best practice to do so for the sake of other flights in the area and air traffic control for the sake of safety. The decision to keep the transponders broadcasting over Russian airspace betrays a desire to make the flight as visible and easily identifiable as possible.

The purpose of the flight is obscure and the type of aircraft does not easily lend itself to determining who or what might be onboard, given such heavy lift transports can be fitted out for VIP or passenger transport, cargo, or vehicle deployment. CBS News reports CIA director John Ratcliffe is in Moscow talks, but this has not been officially confirmed.

As reported, there has been discussion of a potential discussion between Trump envoys Steve Witkoff and Jared Kushner in recent weeks, but to date this talk hasn’t matured into any confirmed discussion. When asked on Tuesday morning, President Vladimir Putin’s official spokesman Dmitry Peskov said his office had no comment on the arrival of an American flight, but Russian state media reported the arrival of an aircraft as fact.

Britain’s UK Defence Journal states the flight triggered particular attention on social media on Tuesday given direct U.S. flights to Russian airports are now very rare given the state of diplomatic relations between the two nations. Furthermore, Russia appears to be withdrawing from what limited diplomatic contact there was in recent weeks.

The report notes video has been posted to Russian social media of a C-17 coming in to land in Moscow, and of a convoy of diplomatic vehicles with foreign plates moving through the city, but clarifies the footage has not been confirmed genuine in either case.

What is certain, however, is the apparently linked flight of another U.S. military plane which also arrived into Latvia over the weekend. The Boeing C-40, a military passenger and VIP aircraft, arrived on Sunday and according to transponder data was parked next to the same C-17 that then went on to Moscow this morning.

This story is developing, more follows