LONDON — The Royal Navy in Britain has been monitoring Russian warships in the North Sea and has escorted one vessel skirting British waters, the Defense Ministry in London said on Tuesday, amid heightened tensions between the two countries.

The Defense Ministry said in a statement that it had noted an “upsurge” in Russian vessels in the region over the past few days, and that it sent the frigate St. Albans to escort the Russian warship Admiral Gorshkov through the North Sea as it neared British waters. A helicopter was dispatched to monitor two other Russian vessels.

“Britain will never be intimidated when it comes to protecting our country, our people, and our national interests,” Defense Secretary Gavin Williamson said in the statement.

It was not the first time Britain had taken such measures against Russian vessels. In January, the Royal Navy escorted a Russian aircraft carrier passing through the English Channel as it returned from Syria. In April, a patrol ship escorted a Ropucha-class landing ship through the English Channel, and there were other episodes involving Russian vessels in May and November.