A rare US reconnaissance aircraft specializing in signals intelligence conducted its second spy flight near Russia’s western border on Monday since reaching Europe last week.

The US Air Force The RC-135U’s flight lasted about nine and a half hours, according to data collected on Monday by flight tracking service Flightradar24. The aircraft, stationed in the United Kingdom since August 18, left Mildenhall Air Base in eastern England.

During its second flight in Europe, the aircraft, named Combat Sent, headed east after takeoff, flying over the Netherlands, Germany and Poland. It continued its spy flight by flying over Lithuania, Latvia and Estonia before crossing the Gulf of Finland and reaching Finland.

According to the Air Force, this aircraft – one of only two in its inventory –can locate and identify Radar signals from foreign armed forces on land, at sea and in the air. The information obtained from the data helps to determine detailed operational characteristics and capabilities of foreign systems.

NewsweekThe map of with Coordinated Universal Time (UTC) shows the flight route of the aircraft in Eastern Finland.which borders Russia. The aircraft circles the Finnish territory several times before returning to its temporary base in Mildenhall. On the return flight it flies directly over the Baltic Sea.

The American spy plane flew twice around the Russian city of Kaliningrad on Monday, which lies between NATO members Poland and Lithuania. The area has been under the control of the Russian Leningrad Military District since March in response to Finland and Sweden joining NATO.

On Tuesday, the same plane flew and circled over the waters off Kaliningrad. According to flight tracking data, it was the third flight in Europe and lasted over five hours.

The Combat Sent is deployed worldwide for peacekeeping and emergency operations. From May 7 to 14, it conducted five flight operations near the Chinese coast from its forward operating base on the Japanese island of Okinawa. On May 17, it also flew a nearly nine-hour mission over South Korea.

Meanwhile, an RQ-4B Global Hawk, an unmanned American spy plane, arrived at Fairford Air Force Base in England on Thursday for a temporary deployment, part of an effort to diversify operating locations and improve integration with NATO allies, the Air Force said in a statement.

Flight tracking data also showed that the Global Hawk took off from Sigonella Air Base in Italy and was in the air over the Baltics and Finland for around 23 hours before landing at Fairford.

Open source intelligence analyst Amelia Smith said on X (formerly Twitter) that this was the first time an American RQ-4B had been deployed in the UK and the second time it had flown over Finland.

The Global Hawk uses multiple sensors to provide continuous, near-real-time coverage and a flight endurance of over 30 hours, giving it the flexibility to meet mission requirements. In 2014, it completed a 34.3-hour flight, the longest non-refueling flight by a U.S. Air Force aircraft.