BRUSSELS

 Nordic nations have agreed to boost their defense ties and increase solidarity with Baltic States, calling Russia "the biggest challenge to European Security."

Defense ministers of Norway, Sweden, Denmark, Iceland and Finland said in a joint declaration on Thursday that their countries must be prepared for emergencies that may arise.

The ministers said in the declaration published in the Norwegian daily Aftenposten on Thursday: "(Russia) has shown that it is ready to use military means to achieve their political goals, even when it involves violations of international law."

"There is increasing military and intelligence activity in the Baltics and in our northern areas," the ministers said.

"The Russian military is challenging us along our borders and there have been several border infringements in the Baltics," they added.

The statement comes amid deteriorating relations between Russia and Europe in the wake of the Ukraine crisis and the annexation of Crimea.

The heightened tensions have also led to the traditionally neutral Scandinavian countries upgrading their defense capabilities. Finland and Sweden are not NATO-member countries, but they have increased their cooperation with the Alliance in response to what they call "Russian aggression."

Sweden accused Russia in October last year of having a submarine in Swedish territorial waters. Russian Defense Ministry spokesman Igor Konashenkov later accused the Swedish government of hyping-up tensions in the Baltic Sea region.

Sweden and Denmark also summoned their respective Russian ambassadors in December in response to a Russian military plane reportedly turning off its location device and nearly colliding with a Swedish civilian airliner.

Russia was accused of violating Finnish airspace with its aircraft three times in a week in late August 2014 and twice in May the same year. 

Under the joint agreement, Nordic countries will exchange information about their airspace and on how to meet cyber attacks. The joint statement also said the countries would conduct joint military training operations.

Experts say Russia will perceive the joint declaration as aggression and will react.