Latvia on Monday said it detected a Russian military transport plane flying Monday near its border over the Baltic Sea on Monday. "Patrol planes above the neutral waters of the Baltic Sea near the Latvian outer sea border today have identified a plane of Russian Air Forces - Antonov An-22," the Latvian Armed Forces said in a statement, reported Russian news agency Tass. It was unclear what was being transported in the aircraft.

The close approach on Latvia's border is just the latest in a series of similar occurrences, according to Latvia's defense ministry. Last week, Russian ships and a submarine were allegedly detected just outside of the Latvian border, Russia Today reported. In total, there have been more than 250 recent approaches near the border from Russian aircraft or vessels, according to Latvian officials.

The United Kingdom has also dealt with Russian aircraft making high-profile flights near its territory. The U.K.'s Royal Air Force intercepted Russian bombers flying near British air space in mid-April, CNN reported. That follows an incident in which the Russian ambassador to Britain was called to the U.K.'s Foreign Office in January to explain Russian flights over the English Channel.

Two bombers "caused disruption to civil aviation" and came close to -- but did not cross into -- British air space, according to the foreign office, CNN reported. The aircrafts were once again intercepted by U.K. fighter jets and were escorted out of the area. "All flights of the air forces have been made in strict compliance with international law on use of air space above neutral waters and without having crossed borders of other countries," the Russian Defense Ministry said at the time, according to Tass.

NATO said more than 400 Russian flights were scrambled by its members in 2014, a 50 percent increase from the year before, CNN reported. The Russian Defense Ministry said that the United States made 137 flights near its border in 2014, according to Tass.