Britain's defense secretary says NATO members Romania and Britain will not be intimidated by threats against members of the military alliance.

Russia's ambassador to Denmark, Mikhail Vanin, said this weekend that Danish warships could become targets for Russian nuclear missiles if the Danes join the alliance's missile defense system. Bases are planned in the southern Romanian town of Deveselu and in Poland.

"Neither Romania nor Britain will be intimidated by threats to its alliance or its members," Defense Secretary Michael Fallon said Monday during a one-day visit.

He said Britain would send one of its newest destroyers to the Black Sea port of Constanta in the fall. "We share Romania's concern about threats to security on the Black Sea region."

NATO decided in January to set up command-and-control centers in Latvia, Estonia, Lithuania, Poland, Romania and Bulgaria by the end of 2016 in response to challenges from Russia and Islamic extremists and to reassure eastern partners.

Romania will also host a multinational division headquarters for the southeast and Poland will have a similar one for the northeast. In an emergency, the centers would help speed up the arrival of the new quick-reaction force.