Kim Jong-Un visits the Ministry of People's Security on Wednesday, May 1, as part of the country's May Day celebrations.
A North Korea soldier gestures to stop photographers from taking photos from a Chinese tour boat as other soldiers look on along the North Korean bank of the Yalu River near the town of Sinuiji across the Chinese city of Dandong in Liaoning province, China, on Saturday, April 6. North Korean leader Kim Jong Un has ordered the country's military to increase artillery production, a televised report out of Pyongyang showed on Saturday.
North Korean soldiers gather by the docks in Sinuiju near the Chinese border on Thursday, April 4.
North Korean soldiers patrol along the Yalu River in Sinuiju across the border from the Chinese city of Dandong on April 4.
Kim Jong Un is briefed by his generals in this undated photo. On the wall is a map titled "Plan for the strategic forces to target mainland U.S."
Kim Jong Un works during a briefing in this undated photo.
North Korean leader Kim Jong Un inspects drills by the Korean People's Army navy at an undisclosed location on North Korea's east coast on March 25 in a photo from the state-run Korean Central News Agency.
Kim makes his way to an observation post with North Korean soldiers on March 25.
Kim uses a pair of binoculars to look south from the Jangjae Islet Defense Detachment near South Korea's Taeyonphyong Island on March 7.
Kim is greeted by the family of a soldier as he inspects Jangjae Islet Defense Detachment near South Korea's Taeyonphyong Island in South Hwanghae province on Thursday, March 7, in a photo from the state-run Korean Central News Agency.
Kim is surrounded by soldiers during a visit to the Mu Islet Hero Defense Detachment near South Korea's Taeyonphyong Island on March 7. North Korea has escalated its bellicose rhetoric, threatening nuclear strikes, just before the U.N. Security Council passed tougher sanctions against the secretive nation on March 7.
Kim arrives at Jangjae Islet by boat to meet with soldiers of the Jangjae Islet Defense Detachment near Taeyonphyong Island in South Hwanghae province on March 7.
Soldiers in the North Korean army train at an undisclosed location on March 6.
North Korean leader Kim Jong Un, center, poses with chiefs of branch social security stations in this undated picture released by North Korea's official news agency on November 27.
Kim celebrates with staff from the satellite control center in Pyongyang, North Korea, during the launch of a rocket carrying a satellite, in a photo released by the official North Korean news agency on December 12.
A crowd watches as statues of the nation's founder, Kim Il Sung, and his son Kim Jong Il are unveiled during a ceremony in Pyongyang on April 13, 2012. Photos from North Korea are rare, but the country was on full display in April 2012 as it celebrated the 100th birthday of Kim Il Sung.
A North Korean soldier stands guard in front of an UNHA III rocket at the Tangachai-ri Space Center on April 8, 2012.
In April 2012, Pyongyang launched a long-range rocket, which broke apart and fell into the sea. The UNHA III rocket is pictured on its launch pad in Tang Chung Ri, North Korea.
A closer look at the UNHA III rocket on its launch pad in Tang Chung Ri, North Korea.
A military vehicle participates in a parade in Pyongyang on April 15, 2012.
North Koreans wave flags in front of portraits of Kim Il Sung, left, and his son Kim Jong Il during celebrations to mark the 100th birth anniversary of Kim Il Sung in Pyongyang on April 16, 2012.
North Korean soldiers relax at the end of an official ceremony attended by leader Kim Jong Un at a stadium in Pyongyang on April 14, 2012.
Kim Jong Un applauds as he watches a military parade in Pyongyang on April 15, 2012.
A North Korean soldier stands on a balcony in Pyongyang on April 16, 2012.
North Korean soldiers march during a military parade in Pyongyang on April 15, 2012.
Soldiers board a bus outside a theater in Pyongyang on April 16, 2012.
North Korean performers sit below a screen showing images of leader Kim Jong Un in Pyongyang on April 16, 2012.
North Korean soldiers salute during a military parade in Pyongyang on April 15, 2012.
Kim Jong Un visits the Rungna People's Pleasure Ground, which is under construction in Pyongyang, in a photo released on July 3, 2012, by North Korea's official Korean Central News Agency.
North Korean soldiers listen to a speech during an official ceremony attended by leader Kim Jong Un at a stadium in Pyongyang on April 14, 2012.
Members of a North Korean military band gather following an official ceremony at the Kim Il Sung stadium in Pyongyang on April 14, 2012.
North Korean military personnel watch a performance in Pyongyang on April 16, 2012.
A North Korean controller is seen along the railway line between Pyongyang and North Pyongan province on April 8, 2012.
A North Korean military honor guard stands at attention at Pyongyang's airport during a diplomatic visit on May 2, 2001.
Kim Jong Un and North Korea's military
Kim Jong Un and North Korea's military
Kim Jong Un and North Korea's military
Kim Jong Un and North Korea's military
Kim Jong Un and North Korea's military
Kim Jong Un and North Korea's military
Kim Jong Un and North Korea's military
Kim Jong Un and North Korea's military
Kim Jong Un and North Korea's military
Kim Jong Un and North Korea's military
Kim Jong Un and North Korea's military
Kim Jong Un and North Korea's military
Kim Jong Un and North Korea's military
Kim Jong Un and North Korea's military
Kim Jong Un and North Korea's military
Kim Jong Un and North Korea's military
Kim Jong Un and North Korea's military
Kim Jong Un and North Korea's military
Kim Jong Un and North Korea's military
Kim Jong Un and North Korea's military
Kim Jong Un and North Korea's military
Kim Jong Un and North Korea's military
Kim Jong Un and North Korea's military
Kim Jong Un and North Korea's military
Kim Jong Un and North Korea's military
Kim Jong Un and North Korea's military
Kim Jong Un and North Korea's military
Kim Jong Un and North Korea's military
Kim Jong Un and North Korea's military
Kim Jong Un and North Korea's military
Kim Jong Un and North Korea's military
Kim Jong Un and North Korea's military
Kim Jong Un and North Korea's military
Kim Jong Un and North Korea's military
STORY HIGHLIGHTS
- Steps to expand missile defenses will cost $1 billion
- Defense Secretary Hagel says 14 more missile interceptors will be deployed by 2017
- NEW: N. Korea rocket launch, nuke test, mobile missile and threats prompt action
- U.S. to work with Japan to increase radar capability to improve early warning, tracking
(CNN) -- The United States will deploy additional ground-based missile interceptors on the West Coast as part of efforts to enhance the nation's ability to defend itself from attack by North Korea, Defense Secretary Chuck Hagel announced Friday.
Still relatively new in his post, the Pentagon chief told reporters that 14 additional interceptors to be installed by 2017 would bring the total to 44. It is part of a package of steps expected to cost $1 billion, officials said.
"The reason that we are doing what we are doing and the reason we are advancing our program here for homeland security is to not take any chances, is to stay ahead of the threat and to assure any contingency," Hagel said.
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Friday's move came after North Korea recently threatened a pre-emptive nuclear attack on South Korea and the United States in response to stepped-up U.N. Security Council sanctions over its latest nuclear test last month.
In December, North Korea successfully launched a long-range rocket for the first time under what the United States and other Western nations say was the guise of putting a satellite into orbit.
Moreover, Pentagon officials said they became concerned about a mobile missile spotted in a parade last April. The KN-08 missile can be moved around the country and hidden, making it harder to detect compared to a missile on a launch pad.
"We believe the KN-08 does have the range to reach the United States," said Adm. James Winnefeld.
North Korea also said last week it was nullifying the joint declaration on the de-nuclearization of the Korean Peninsula. One of the country's top generals, according to published reports, claims Pyongyang has nuclear-tipped intercontinental ballistic missiles that are ready to be fired.
While Hagel said the steps he announced were aimed at addressing the threat from North Korea and Iran, the focus was clearly on the potential for North Korea to some day follow through on its belligerent rhetoric.
Iran also is believed to be continuing its efforts to develop nuclear weapon capability.
Military and White House officials have said current U.S. missile defenses are adequate for the present level of threat, and President Barack Obama said in an interview with ABC News this week that he does not think North Korea can carry out a missile attack on the United States.
"They probably can't but we don't like the margin of error," Obama said.
Hagel said Friday that U.S. missile defense systems in place provide protection from "limited ICBM attacks," but added that "North Korea, in particular, has recently made advances in its capabilities and has engaged in a series of irresponsible and reckless provocations."
However, Joe Cirincione of the Ploughshares Fund told CNN the planned expansion would only spend more money on a system that doesn't work to protect against a still unrealized North Korean threat.
The existing missile defense system was "deeply flawed," said Cirincione, whose foundation opposes nuclear weapons. He added that North Korea was "years away from the ability to field a missile with a nuclear warhead that could hit the United States."
Hagel acknowledged a problem with the guidance system of missile interceptors and said further testing would occur this year.
"We certainly will not go forward with the additional 14 interceptors until we are sure that we have the complete confidence that we will need," Hagel said. "But the American people should be assured that our interceptors are effective."
He also announced the military will work with Japan to increase radar capability to improve early warning and tracking of any missile launched from North Korea.
North Koreans ready to 'rain bullets on the enemy'
Asked how China would react to Hagel's announcement, Undersecretary of Defense for Policy James Miller said: " I hope that they understand that we need to take steps to protect ourselves from potential threats from Iran and North Korea."
Part of the move announced by Hagel would involve reopening a missile field at Fort Greely, Alaska.
In 2011, the Pentagon mothballed Missile Field 1, acting on direction from the Obama administration. Instead of permanently decommissioning it, the Defense Missile Agency placed it in a non-operational state.
Pentagon officials testified at a budget hearing at the time that hardening and reactivating the six silos in Missile Field 1 would take two years and cost approximately $200 million. Pentagon officials testified then that "there are no current threats dictating the need, nor plans to reactivate MF-1 in the future."
Republican congressional sources told CNN that they argued against the move.
"North Korea was doing all sorts of things we couldn't talk about publicly back then," said one GOP congressional official who is privy to intelligence briefings. "The intelligence did not change. This is right where we expected North Korea to be. It takes about two years to order and take delivery of a new interceptor. That's why you have to be ahead of the threat."
In his State of the Union address last month, Obama said the United States would "stand by our allies, strengthen our own missile defense and lead the world in taking firm action in response to these threats."
Last week, Miller told the Atlantic Council that "North Korea's shrill public pronouncements underscore the need for the U.S. to continue to take prudent steps to defeat any future North Korean" intercontinental ballistic missile.
A look at North Korea's escalating rhetoric
CNN's Tom Cohen, Elise Labott, Jill Dougherty and Pam Benson contributed to this report.