WASHINGTON >> Secretary of State John Kerry said today the U.S. may need “more forceful ways” of dealing with North Korea if it develops an intercontinental ballistic missile that threatens America.

Speaking at the U.S. Naval Academy, Kerry said nuclear weapons in the hands of North Korea’s “reckless dictator” Kim Jong Un pose one of the most serious national security challenges to the United States.

Kerry urged Donald Trump’s incoming administration to work closely with China, Pyongyang’s main trading partner, to exert more economic pressure on North Korea.

He said the aim should be resuming talks on denuclearization that could open the way to economic assistance for North Korea, sanctions relief and a formal peace on the divided Korean Peninsula.

But Kerry said if the North persists in developing the long-range missile it “drags the United States into an immediate threat situation to which we may then have to find other ways, more forceful ways of having an impact on the choices that he is making.” Kerry didn’t elaborate.

Kim announced in his annual New Year’s address that the country had reached the “final stages” of intercontinental ballistic missile development. Trump responded with a tweet, saying “It won’t happen!” but did not indicate how his administration would prevent it.

Over the past eight years, the Obama administration has cranked up sanctions on Pyongyang, invested more in missile defense and staged occasional shows of military force. But its policies have failed to stall North Korea’s nuclear weapons and missile programs.

The North conducted two underground nuclear explosions and more than two dozen missile test launches last year.