Poland’s border service will erect six guard towers at the frontier with the Russian exclave of Kaliningrad in June, the Polish news agency PAP reports. The towers are expected to oversee border operations as well as add another layer of security against recent Russian hostility in the region. The development comes amid rising tension between Poland and its eastern neighbor and former master over the Ukrainian war.

"We are continuing to work on putting these towers into operation and testing the equipment installed on the towers. We are planning a full launch by June," said the spokeswoman for Poland’s Mazur-Warmiński Branch Border Service, Miroslava Alexandrovich.

Since Russia annexed Crimea in March 2014 and began assisting pro-Russian rebels in eastern Ukraine, Poland has been beefing up its security arrangements. As well as taking part in NATO exercises, Poland has formally invited U.S forces to be permanently stationed on its territory.

The request comes not long after a U.S. Patriot anti-aircraft and anti-missile battery was placed near Warsaw. The battery came with 100 U.S. troops and around 30 vehicles. Poland is also spending more on defense: Its defense spending will hit NATO’s suggested 2 percent of GDP in the coming year, moving up from 1.95 percent in 2014. This makes Poland one of the biggest spenders on defense in Europe, moving ahead of the economic giants of Europe, the U.K., France and Germany, in percentage terms.

The towers will cost around $4 million, according to Poland’s Border Service, which also said last year 3.2 million Poles and 3.3 million Russians crossed the Kaliningrad border, the only frontier shared by Russia and Poland. Kaliningrad is part of the former German East Prussia, which was taken by the Soviets after World War II.

"The towers, with heights of 35 meters [115 feet] and 50 meters [164 feet], like 11-story and 15-story buildings, will be installed at different distances from each other along the 200-kilometer [135-mile] stretch of the border between Poland and the Russian exclave. The equipment will allow monitoring the situation on the border day and night," Alexandrovich said.