The United States is planning to bolster its missile defence system in Alaska to counter the growing threat from North Korea and Iran.
The Pentagon says it intends to put in place up to 14 new interceptors to expand the system's ability to shoot down any long-range missiles in flight before they can threaten American territory.
A new radar station will be established in Japan.
The new missiles will almost double the capacity the US already has in Alaska and California.
US Defence Secretary Chuck Hagel cited a "series of irresponsible and reckless provocations" by North Korea recently, the BBC reports.
Tensions have risen after Pyongyang's third nuclear test last month.
Mr Hagel says Washington is determined to remain one step ahead of North Korea.
"By taking the steps I've outlined today we will strengthen our homeland defence, maintain our commitments to our allies and partners and make clear to the world that the United States stands firm against aggression."
Officials in Washington have long viewed with concern the combination of North Korean long-range rocket tests and the country's avowed attempts to arm itself with nuclear warheads.