Underestimating the power of North Korea's nuclear weapons would be a grave mistake for the U.S., former Central Intelligence Agency (CIA) Director James Woolsey wrote in an op-ed in the Hill on Wednesday. In fact, the country's missiles equipped with nuclear missiles not only have the ability to reach America but could "blast a U.S. city," he added.

"The mainstream media, and some officials who should know better, continue to allege North Korea does not yet have capability to deliver on its repeated threats to strike the U.S. with nuclear weapons," the op-ed began. "False reassurance is given to the American people that North Korea has not “demonstrated” that it can miniaturize a nuclear warhead small enough for missile delivery, or build a reentry vehicle for an intercontinental ballistic missile (ICBM) capable of penetrating the atmosphere to blast a U.S. city."

Read: McCain Insults North Korea, Again

Woolsey's words came as North Korea and its leader Kim Jong Un have both ramped up rhetoric against the U.S. as well as conducted multiple missile launches in recent weeks that were in clear violation of United Nations Security Council sanctions.

The missile launches have put regional nations and the world alike on edge, prompting South Korea to alert its military to be ready to respond to provocations from Pyongyang with "on-the-spot" and "decisive" military action.

U.S. Secretary of State took on a similar tone during a trip to southeast Asia this week, telling reporters that "all options are on the table" when it comes to responding to North Korea's seemingly never-ending series of ballistic missile test and launches.

North Korea threatened to "mercilessly smash the enemy's moves with its own style of special operation and preemptive attack," an apparent reference joint military drills with South Korea and the U.S. Pyongyang launched its third missile test of the month on March 22, but it failed.

Read: North Korea's Leaflets Condemn US, South's Military Drills

Woolsey said the threat from North Korea remained very real despite perceived shortcomings in the country's nuclear program.

"Even if it were true that North Korea does not yet have nuclear missiles, their 'Dear Leader' could deliver an atomic bomb hidden on a freighter sailing under a false flag into a U.S. port, or hire their terrorist allies to fly a nuclear 9/11 suicide mission across the unprotected border with Mexico," Woolsey wrote. "In this scenario, populous port cities like New York, New Orleans, Los Angeles, and San Francisco, or big cities nearest the Mexican border, like San Diego, Phoenix, Austin, and Santa Fe, would be most at risk."

Read the full op-ed here.