International security

Why has Russia boosted submarine patrols?

Russian attack submarines, the most in two decades, are prowling the coastlines of Scandinavia and Scotland, the Mediterranean Sea and the North Atlantic in what Western military officials say is a significantly increased presence aimed at contesting U.S. and NATO undersea dominance.

Adm. Mark Ferguson, the U.S. Navy’s top commander in Europe, said last fall that the intensity of Russian submarine patrols had risen by almost 50 percent in the past year, citing public remarks by the Russian navy chief, Adm. Victor Chirkov. Analysts say that tempo has not changed since then.

The patrols are the most visible sign of a renewed interest in submarine warfare by President Vladimir Putin, whose government has spent billions for new classes of diesel- and nuclear-powered attack submarines that are quieter, better armed and operated by more proficient crews than in the past.