The operation will take place on June 17 to 19 as part of the international exercise Iron Wolf 2017 and will involve around 1,500 Lithuanian, Polish, British and US troops, as well as heavy military equipment and helicopters.

"This will be the first ever such operation. One of our goals is to train the arrival of allies in Lithuania. This is a purely tactical procedure: how they cross our border and the territory under our forces' control and move further into the Republic of Lithuania," Brigadier General Valdemaras Rupsys told reporters on Monday.

The Suwalki gap is a land strip of around 100 kilometers on the Lithuanian-Polish border that is wedged between the Russian exclave of Kaliningrad on the west and Belarus on the east. In a military conflict, the seizure of the land corridor would cut off the land route for NATO allies to the Baltic countries. Therefore, military experts often describe the Suwalki gap as an Achilles heel.