The U.S. is deploying 14 new ground-based missile interceptors in Alaska to counter renewed nuclear threats from North Korea and Iran, Defense Secretary Chuck Hagel said Friday.

The new interceptors will be based at Fort Greely, an Army launch site about 100 miles southeast of Fairbanks, Alaska, and are projected to be fully deployed by 2017, Hagel said. The additions will bring the U.S.-based ground interceptor deployment from 30 to 44, including four that are based in California.

That will boost U.S. missile defense capability by 50 percent and “make clear to the world that the United States stands firm against aggression,” he said in a briefing at the Pentagon.

The announcement comes as North Korea has been making bellicose threats to void the armistice that ended the Korean War and launch a nuclear attack on the U.S. The U.S. and South Korea began annual military drills this week despite the North Korean threats.