OSLO (Reuters) - NATO allies Britain and Norway agreed on Thursday to beef up their defense cooperation, including maritime surveillance and joint exercises on Norwegian soil, amid concerns about a more assertive Russia in northern Europe.

The two countries signed the deal during a visit by British Defence Secretary Michael Fallon to Norway’s Arctic region, Norway’s defense ministry said in a statement.

“Given our geographical vicinity and common challenges in connection to the strategic situation in the North Atlantic, we are well positioned for future cooperation in maritime surveillance,” Norwegian Defence Minister Ine Eriksen Soereide said.

“The continuation of capacity for surveillance and anti-submarine operations are important for NATO and close allies”.

Neighboring Sweden and Finland, which are not in the NATO alliance, have expressed concerns about incursions by Russian submarines and other naval vessels.

Norway’s statement did not specifically mention a Russian military threat as the cause for the increased cooperation.

In a 2015 interview with Reuters, Soereide said Norway was concerned about what she called an “obvious projection of power” by Russia in the Baltic Sea region, where Russian military flights increased threefold from 2013 to 2014.

Relations between NATO and Russia have been badly strained in recent years, especially since Moscow’s annexation of Ukraine’s Crimea region in 2014.

Now NATO’s European member states are nervously awaiting clarification of U.S. President-elect Donald Trump’s geopolitical stance following his criticisms of the Atlantic alliance and his praise for Russia’s President Vladimir Putin.

Britain is keen to use NATO as the main conduit of European defense policy, vowing in October to block any attempt by the European Union to create its own army while it remains a member of the bloc. Britain is due to quit the EU in the coming years.

Norway, a founding member of NATO, is not in the EU.