With no end in sight for tensions in Eastern Europe, Lithuania’s Defense Ministry reported Tuesday that NATO jets were scrambled 160 times during 2015 in response to intercepting Russian planes, the Associated Press reported. Spain and Belgium this week are expected to take over NATO's Baltic Air policing mission from Hungary and Germany.

The interceptions mark a 14 percent increase from 2014, when 140 jets were scrambled. In 2013 only 47 jets were scrambled, underscoring increasing Russian aircraft presence in the Baltic region following the country's annexation of Crimea from Ukraine in March 2014. The conflict in Eastern Ukraine that has pitted Ukrainian forces against Russian-backed separatists and left more than 9,000 people dead has also increased regional tensions and security concerns of neighboring states.

NATO, the 28-member military and political alliance, has described its policing mission of Baltic airspace in terms of security as Eastern European and Baltic States continue to call for a greater NATO presence in the region.

“[The] efforts are focused on stopping incursions into NATO airspace and on preventing acts of air terrorism,” the organization said.

Russian President Vladimir Putin has long described NATO as encroaching on Russia’s regional sphere of influence, a claim the alliance has continued to deny.

“We categorically reject totally unfounded claims that NATO and its policies constitute a security threat,” Oana Lungescu, a spokesman for NATO, said.

NATO has moved closer to Russia and held military exercises in Poland, deploying temporary units there. Poland’s foreign minister said Monday that permanent NATO troops could be stationed in his country’s territory after a NATO summit is held in Warsaw in July.

“The term ‘bases’ is avoided as reminiscent of Cold War confrontation attitudes, but there are signs that indicate that such presence will be guaranteed,” Witold Waszczykowski said.

NATO does not have a permanent base in Eastern Europe. The July summit is expected to focus on security in the region and also welcome Montenegro to the alliance, another move Russia has protested.