U.S. Secretary of Defense Chuck Hagel announced Friday that his country will deploy 14 additional ground-based interceptor missiles in Alaska by 2017, a move which apparently reflects that Washington is taking North Korea's long-range missile threats more seriously.

The Pentagon also plans to set up a new radar station in Japan to beef up its capability to detect any missile fired from the secretive communist nation.

"I'm announcing a series of steps the United States will take to stay ahead of the challenge posed by Iran and North Korea's development of longer-range ballistic missile capabilities," Hagel said at a press conference.

"The United States has missile defense systems in place to protect us from limited ICBM attacks, but North Korea in particular has recently made advances in its capabilities and is engaged in a series of irresponsible and reckless provocations," he added.

Currently the U.S. has 30 ground-based interceptors (GBIs) on on the West Coast. There are four GBIs at an Air Force base in Floria.

Hagel gave reassurances about the effectiveness of the costly missile defense system.

"We have confidence in our system...The American people should be assured that our interceptors are effective," he said.

Concerns have grown in the U.S. about North Korea's missile capability. In December, North Korea succeeded in putting a satellite into orbit, followed by another nuclear test. It claimed to have tested a miniaturized bomb, while it remains unconfirmed whether uranium was used.

In recent weeks, Pyongyang has been threatening to launch a nuclear-tipped missile at the U.S.

Joining the press conference, Adm. James Winnefeld, vice chairman of the Joint Chiefs of Staff, admitted that Pyongyang's missile threat "went just a little bit faster" that the U.S. might have expected.

He noted that the North's road-mobile intercontinental ballistic missile, known as KN-08, is believed to have the range to reach the U.S. mainland.

Asked whether a missile displayed by the North in last year's military parade was a real KN-08 or a fake, he refused to go into details, saying it was classified information.

He said the U.S. has about five Aegis ships with ballistic missile defense capabilities in the Asia-Pacific region.

The Pentagon's move to strengthen missile defense, expected to cost hundreds of millions of dollars, comes despite increasing pressure to slash its budgets.

The Obama administration is also conducting environmental impact studies for a potential GBI site on the East Coast.

No decision has been made yet on whether to proceed with an additional site but the studies will shorten the timeline for a decision, according to Pentagon officials.

They said they are in consultations with Japan for the schedule to install new radar, code-named TRY-2, a process likely to take at least several months.

They said the U.S. gave prior notice to China about the plans to boost the missile defense system. They would not characterize Beijing's response, however. (Yonhap News)