MOSCOW (AP) — Russian President Vladimir Putin has hailed the military’s performance during recent Arctic drills, part of Moscow’s efforts to expand its presence in the polar region. Navy chief Adm. Nikolai Yevmenov reported to Putin Friday that the exercise has featured three nuclear submarines simultaneously breaking through Arctic Ice and warplanes flying over the North Pole. This week’s drills were conducted around Alexandra Land, an island that is part of the Franz Josef Land archipelago. Russia has prioritized beefing up its military presence in the Arctic region, which is believed to hold up to one-quarter of the Earth’s undiscovered oil and gas. Putin in the past has cited estimates that put the value of Arctic mineral riches at $30 trillion.