Peskov’s comment came after a statement by NATO’s Joint Support and Enabling Command (JSEC) Chief Lieutenant-General Alexander Sollfrank about the need for a “military Schengen,” a free military passage zone similar to the political Schengen zone that allows the armed forces to move freely.

The suggestion caused concerns for Russia and “may lead to retaliatory measures” to ensure its security, the spokesman said.

The Schengen area was established in March 3, 1995, and is the world’s largest free travel area consisting of 27 countries, including 23 EU states. The region abolished many forms of border controls.