Ten Russian submarines were spotted simultaneously in the Norwegian Sea and the North Atlantic, said the NATO spokesperson Oana Lungescu, as cited by RND.
"Russia is constantly increasing its underwater capacity," Lungescu said.
She pointed out that the activity of Russian submarines this year has reached the highest level since the end of the Cold War.
"NATO will respond to this, in particular, with more patrols. In addition, NATO will invest in modern anti-submarine aerial combat capabilities," she said in a statement.
According to the NATO representative, military supply routes, civilian trade routes and communication channels of the North Atlantic remain "vital to Europe's security".