Estonia protested after a Russian military cargo plane has violated its airspace near Vaindloo Island in the Baltic Sea.

The incident on March 12 was the first alleged airspace violation of Estonia by a Russian plane this year after the Baltic nation reported several similar intrusions in 2017 and 2016.

Estonia’s military said the Il-76 plane spent less than a minute in the country’s airspace.

It said the aircraft’s transponder was switched on and a flight plan had been presented to Estonian authorities, but the plane maintained no radio contact with Estonia’s air navigation service.

Estonia’s Foreign Ministry handed Russia’s ambassador a protest note over the incident, though the Russian Defense Ministry denied violating Estonian airspace.

“The flight was performed in strict compliance with the international rules of the use of airspace. The borders of other states were not violated, which was confirmed by objective monitoring means,” the ministry said in a statement.

Vaindloo is near a corridor where Russian military and cargo planes fly to get from the St. Petersburg area to the Russian Baltic Sea enclave of Kaliningrad.

Encounters between Russian and NATO warplanes have increased as Moscow has demonstrated its resurgent military might.

Russia also has increased its navy’s presence in the Mediterranean, Black Sea, and other areas.

In January, two Belgian F-16 fighters jets as well as two British Typhoon planes intercepted a couple of Russian strategic bombers near UK and Dutch airspace.

The incident on Monday came on the day when European Union extended its sanctions against Russia, imposed over the annexation of Crimea and supporting rebels in eastern Ukraine, for another six months.

The sanctions, including travel restrictions and asset freezes against 150 people and 38 companies, would be extended until Sept. 15, the European Council said.

“An assessment of the situation did not justify a change in the sanctions regime,” the Council said in a statement.

After annexing Crimea in 2014, in a move that has not been recognized internationally, Russia said it would not return the region.

The EU and other Western countries say Russia has also been providing a lifeline to separatists in eastern Ukraine, where a conflict has killed more than 10,000 people since 2014.