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President Donald Trump will make his first address to the United Nations General Assembly on Tuesday, projecting his "America First" platform onto the world stage with an appeal for "burden sharing" in the face of global challenges and putting North Korea squarely in his sights.

Trump will call on nations "to do their part in confronting" the threat of "rogue regimes," like North Korea and Iran, a senior administration official told reporters in a briefing on Monday.

The North Korea "menace" will be a central focus of the president's address, the official said, adding that Trump will paint a picture of an increasingly dire situation in the face of inaction.

Big day at the United Nations - many good things, and some tricky ones, happening. We have a great team. Big speech at 10:00 A.M. — Donald J. Trump (@realDonaldTrump) September 19, 2017

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In a tweet over the weekend, Trump referred to North Korea's leader as "Rocket Man" — an apparent reference to the country's recent repeated missile tests.

"If we don't confront these threats now, they will only gather force and become more formidable," the official said.

The White House has long held an "all options on the table" approach to North Korea, declining to negotiate or telegraph its plans publicly. Defense Secretary James Mattis said on Monday that "there are many military options, in concert with our allies" for North Korea.

The White House declined to offer specifics on what Trump might press for during his UN address in regard to action against North Korea.

"Everyone in the world who needs to be delivered a message in the speech will understand what messages are being delivered to them, and in the way and fashion in which that message is being delivered," the official said.

The stakes for Trump's speech are high, with political watchers and the world community anxiously waiting to see what the mercurial president — who has had strained interactions with some longtime U.S. allies since taking office — will say.

The White House did nothing to tamp down on the importance of the address, with the senior official calling it an "incredible moment and an enormous opportunity to demonstrate U.S. leadership and U.S. values.

"And that's why the president has, again, spent so much time honing and crafting this address to express that vision to the world," the official added.

Earlier Monday, during a session focused on reforming the United Nations, Trump offered his support for reform while stressing the importance "that no one and no member state shoulders a disproportionate share of the burden, and that's militarily or financially."