Defense Secretary Chuck Hagel announced plans on Friday, March 15 to bolster missile defenses in response to "irresponsible and reckless provocations" by North Korea, which threatened a preventative nuclear strike against the United States last week, Reuters said.

Hagel said the Pentagon would add 14 new anti-missile interceptors at Fort Greely in Alaska - an effective reversal of an early Obama administration decision - and move ahead with the deployment of a second missile-defense radar in Japan.

The Pentagon also left open the possibility of creating a site on the East Coast where the Pentagon could field more interceptors capable of striking down an incoming missile. The 14 additional interceptor deployments would cost nearly $1 billion and must be approved by Congress.

"By taking the steps I outlined today we will strengthen our homeland defense, maintain our commitments to our allies and partners, and make clear to the world that the United States stands firm against aggression," Hagel told a news conference.