North Korea's rapidly improving missile technology capabilities have alarmed Americans. As Kim Jong Un continues to demonstrate his dangerous commitment to advancing his nuclear weapons capabilities and missile program, U.S. policymakers must ensure that our entire nation is protected – including the tens of millions of Americans living along the East Coast.

In November, North Korea launched the Hwasong-15 ICBM over the Sea of Japan. The missile reached the highest altitude ever recorded by a North Korean missile, flying 2,800 miles into the sky before landing off the coast of Japan. The test proves North Korea's ability to successfully target the whole of the continental U.S., and according to Secretary of Defense Jim Mattis, its ability to hit "everywhere in the world, basically."

More concerning, surveillance photos taken over North Korea depict workers assembling what analysts believe to be an operational ballistic missile submarine. North Korea already possesses an experimental submarine with a potential to launch ballistic missiles, so this second operational submarine is a significant improvement in their capability. Submarines make it much more difficult to track, as the threat is constantly moving and expand the range of feasible targets while also improving accuracy. For these reasons, missile defense experts often categorize submarine missile launches as the deadliest and most difficult weapons to counteract. The specific submarine-launched missile North Korea is developing is longer in size, making it even more powerful and effective at evading U.S. defenses.

And North Korea is not an isolated threat. Iran has been working on a ballistic missile program for several decades, currently possesses the capability of delivering a weapon of mass destruction, and has the largest inventory of missiles in the Middle East. While they do not currently have ICBMs, advancements in the burgeoning Iranian space program will quickly accelerate their development, as space launch vehicles use similar technology. Intelligence reports also indicate extensive and consistent cooperation between Iran and North Korea on their respective missile programs.

The U.S. is facing an increasingly hostile threat environment that encompasses not only the North Korean and Iranian threats, but threats from Russia and China as well. These adversaries are challenging us on all fronts, seeking to expand their geopolitical influence and undermine U.S. national security interests. Their improvement of their ICBM programs aimed to deter and constrain the U.S. is no exception.

Currently, the Ground-Based Midcourse Defense system protects the U.S. mainland from this threat. The program is designed to hit an incoming ICBM in between the initial launch and the terminal descent phase. Essentially, our missile defense systems try to hit a bullet with a bullet — there is little room for error.

Tests have shown that with our current capabilities, the U.S. is unable to deter all missile attacks. In its 18 intercept tests to date, the Ground-Based Interceptors have only succeeded 10 times, giving it a roughly 56 percent success rate. Additionally, none of the tests were performed in a realistic environment that accurately simulates an actual ICBM attack. In addition, these tests did not include the use of active countermeasures or imitate the potential trajectory of a North Korean Hwasong-15.

The GMD has two batteries with 44 missile interceptors on the West Coast. These two batteries are responsible for defending the entire continental U.S., leaving the East Coast less protected.

According to The Diplomat, to improve accuracy, the U.S. fires four interceptors to hit each incoming ICBM. This further degrades the capability of the defense system to target and destroy any follow-up ICBM attacks, as fewer interceptors will be available for firing. Should North Korea, Iran, or another adversary use penetration aids to act as decoy re-entry vehicles, even fewer interceptors would be available to hit the real warhead as they would be occupied trying to kill the dummies.

The East Coast is home to our nation's capital, the center of the world's financial system, as well as several significant population centers. As our enemies' capabilities improve, it is reckless to leave the East Coast open to attack.

Building an East Coast Missile Defense site would increase the number of sensors available to track an incoming ICBM and allow for the capability to shoot, assess, and then shoot again. As it currently stands, with sensors only on the West Coast, we do not have that capability. Of the three sites currently under consideration for a third GBI site, the geographic location of Fort Drum – home of the famed 10th Mountain Division in upstate New York – provides the optimal location to employ the shoot-assess-shoot capability.

An East Coast Missile Defense site located at Fort Drum would expand the battlespace, provide greater decision time, protect the entire continental U.S., and offer a different angle of intercept — all factors that significantly increase the accuracy and effectiveness of our continental U.S. missile defense system. Additionally, Fort Drum's existing infrastructure and community support system make it an ideal location from an economic standpoint. Fort Drum's airfield, railroad line on post, and major highway near the installation can easily handle transportation and utility needs. As home of the 10th Mountain Division, the service members and their families stationed at Fort Drum have a rich history of supporting the U.S. military and integrating new families into the North Country.

Next month, the Missile Defense Agency is set to release its Ballistic Missile Defense Review assessing the need for a third missile defense site to guard the continental United States against incoming ICBMs. To protect the entire continental U.S. and deter aggressors, building an East Coast missile defense site located at Fort Drum is in the best interest of U.S. national security.

Elise Stefanik, a Republican, represents New York's 21st Congressional District in the U.S. House. She is a member of the House Armed Services Committee, where she chairs the Emerging Threats and Capabilities Subcommittee. She is the youngest woman ever elected to Congress.

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