By Chris Lawrence, (CNN) — U.S. Defense Secretary Chuck Hagel is expected to announce Friday afternoon that the Pentagon will enhance the nation’s ability to defend itself from a nuclear attack by North Korea, a U.S. defense official told CNN.

Hagel will announce that the United States will deploy up to 14 additional ground-based missile interceptors on the U.S. West Coast, according to the official.

Part of the move would involve reopening a missile field at Fort Greely, Alaska, and some of the interceptors would be based in California. It would take two years for all of the systems to come online.