Denmark and Sweden have announced that they will develop closer defense ties, just as both face increased Russian military activity in the Baltic and Nordic regions. The cooperation, announced at a joint press conference in Copenhagen on Wednesday, could see the two countries share air and maritime surveillance information during peacetime, even though Denmark is a member of NATO and Sweden is a neutral country. 

"We have a long tradition of military cooperation between Denmark and Sweden,” said a joint statement from the Swedish and Danish Defense ministries. “A pragmatic and determined effort will be made to enhance Danish-Swedish military cooperation in order to achieve increased operational effect and added value to mutual benefit for both countries. We underline the political will and intent to move forward.”

According to a joint military press release, Swedish and Danish Defense Ministers Peter Hultqvist and Nicolai Wammen will meet again in the coming weeks to finalize the process. The cooperation will supplement the preexisting Nordic Defense Cooperation and Sea Surveillance in the Baltic Sea agreements.

Over the past year, both countries have had serious cause for concern as Russian aircraft, ships and submarines have probed closer and closer to their sovereign air space and waters. Sweden in particular has seen at least one incident of what may have been a submarine, which it says was Russian, enter its territorial waters in the past year and has intercepted numerous Russian military aircraft flying in international airspace with transponders off. Denmark has also dealt with similar activity from Russia, including from Russian aircraft and one instance of a ship breaching its territorial waters in 2014.

Tensions between Russia and Europe have been heightened over the past 15 months since Moscow annexed Crimea in March 2014, and Russia has continued to be involved in the eastern Ukraine war since it began in April 2014. Russia denies its involvement.