North Korea could soon have the capacity to launch an attack on Hawaii that would devastate America's Pacific military bases, accelerating the need for the United States to upgrade missile defenses in the area.

The United States today relies on ground-based ballistic missile interceptors deployed in California and Alaska to protect Hawaii, but these defenses would do little to guard U.S. territory in the Pacific against a North Korean intercontinental ballistic missile (ICBM), which officials believe is nearing completion.

The U.S. Missile Defense Agency in February test fired a new SM-3 Block IIA missile from Hawaii that successfully intercepted an incoming ballistic missile, but the Pentagon does not maintain a permanent missile defense installation or detection capabilities on the Hawaiian Islands.

The Pacific Missile Range Facility in Hawaii hosts an experimental, land-based ballistic missile defense system called Aegis Ashore. The facility served as a prototype for the U.S. missile defense facility in Romania, which was declared operational last year, and another in Poland that will be completed in 2018.

Ariel Cohen, director of the Center for Energy, Natural Resources, and Geopolitics at the Institute for the Analysis of Global Security, told the Washington Free Beacon on Tuesday that the Defense Department needs to immediately upgrade the Aegis Ashore facility in Hawaii from experimental to operational to guard against North Korean aggression.

"Senior national security leaders have stated that the U.S. needs to work off the assumption that North Korea will have ICBM capabilities soon, and in this business ‘soon' could mean five to 10 years, or earlier," Cohen said.

"This question is, do we need to wait until North Korea successfully launches a test ICBM to know that they have that capacity? The answer is no … The [Aegis Ashore] is a proven system. Why would we protect our European allies before we protect the homeland?"

Aegis, developed by Lockheed Martin Corp to be used on U.S. Navy destroyers, is one of the most advanced missile defense systems in the world. Deploying the land version of that technology to Hawaii, coupled with Aegis-equipped Navy destroyers, would establish a permanent missile defense installation in the U.S. Pacific that could protect the Hawaiian Islands and the West Coast from a North Korean missile launch.

Converting the Aegis Ashore site from an experimental facility to a combat-ready platform would cost an estimated $41 million, which Cohen described as "inexpensive" compared to typical Defense Department expenditures.

The proposal to improve Hawaii's missile defense capabilities gained support among defense officials on Monday after North Korea launched four missiles that coincided with joint U.S.-South Korean military exercises in the region.

The U.S. joint chiefs initially believed that at least one of the projectiles launched by North Korea was an intercontinental ballistic missile capable of striking America's West Coast, but ultimately concluded the projectiles did not have the range of an ICBM.

Defense officials have warned that North Korea is on the brink of producing an ICBM that could target the United States. North Korean leader Kim Jong Un announced in January during his New Year's address that Pyongyang had "entered the final stage of preparations to test-launch" an ICBM that could reach parts of the United States.

President Donald Trump rejected Kim's assessment, tweeting after the statement: "It won't happen!" The administration has not yet established a missile defense plan that would protect the United States from a North Korean ICBM, though it is in the process of reviewing U.S. policy toward North Korea.

Bruce Klingner, a senior research fellow for Northeast Asia at the Heritage Foundation, told the Washington Free Beacon that the administration will likely look at defense and deterrence tactics to use against Pyongyang, rather than diplomatic engagement.

"Our intelligence has been surprised again and again by technology developments by adversaries or attacks the U.S. didn't foresee," Cohen said. "Hawaii has a particularly symbolic history of this given the attacks on Pearl Harbor. Let's not be surprised this time, let's be prepared."

Pyongyang has worked for years to improve its missile capabilities, launching an unprecedented number of ballistic missiles in 2016 while conducting its fifth nuclear test in September 2016.