Lithuania's army reported on Thursday that two Russian military aircraft had crossed the Lithuanian border, remaining in the NATO member state's airspace for 18 seconds.

The aircraft, a fighter jet and a tanker, flew 700 meters (nearly half a mile) into Lithuania from the Kaliningrad region.

The Lithianian air force detected the Russian SU-30 and IL-78 aircraft near Kybartai at around 6 p.m. (1600 GMT).

Two Spanish air force Eurofighters were scrambled in response to the incursion.

Lithuanian President Gitanas Nauseda called the move a "blatant breach of international law and territorial integrity of Lithuania" in a post on X that said it "confirms the importance of strengthening European air defense readiness."

Nauseda's post also noted that Vilnius' Foreign Ministry would summon Russian embassy representatives to protest Russia's "reckless and dangerous behavior."

Russia denies incursion into Lithuanian airspace

The Russia's Ministry of Defense on Thursday confirmed that its planes were in the air but denied they had entered Lithuanian airspace, albeit without mentioning the Baltic nation by name. 

In a statement on Telegram, the ministry said, "SU-30 fighters carried out a planned training flight over Russia's Baltic Kaliningrad region and violated no borders of other countries."

"The flights took place in strict observance of the rules of using airspace over the territory of the Russian Federation, did not deviate from their flight route and did not violate the borders of other states, which was confirmed by objective control means," the statement continued.

Russian violations of NATO airspace becoming more common

Thursday's incident is just the latest in a series of encroachments in which Russian jets as well as drones have breached NATO airspace.

Poland, Romania, Denmark, Latvia, Estonia and Lithuania have all been subjected to such incursions over the past few weeks.

The situation has alarmed European leaders who accuse Russian President Vladimir Putin of conducting what they call a hybrid war and suggesting that these provocations are designed to terrorize European citizens and test NATO resolve and readiness.

The Baltic nations of Lithuania, Latvia and Estonia, as well as neighboring nations Finland and Poland, all share borders with Russia, putting them squarely at NATO and the European Union's eastern flank.

They also share a special history with Russia.

Each has been invaded and occupied by it at one point or another, and they fear Putin intends to force them back under Moscow's yoke if he is not stopped in Ukraine.

Edited by: Saim Dušan Inayatullah