The president said "tolerance for this disgraceful practice must end now".
Separately, China and Russian Federation began a joint naval exercise east of the Korean peninsula but it is unclear if it is linked to current tensions in the region. Trump spoke by phone with Xi on Monday and praised the leader during multiple sets of remarks here on Thursday for the banking moves, which were reported by Reuters.
Trump's U.N. speech came days after U.S. Defence Secretary Jim Mattis created unease in South Korea by saying without elaboration that the United States has military options against North Korea that wouldn't involve the destruction of Seoul.
After its two successful intercontinental ballistic missile tests in July, North Korea in early August had threatened to strike Guam in response to US President Donald Trump's rhetoric that any threat by Pyongyang would be "met with fire and fury like the world has never seen".
"The bottom line is: The missiles, were they to be a threat - whether it be to USA territory, Guam, [or] obviously Japan's territory - that would elicit a different response from us", he said.
Trump spoke Thursday at a meeting in NY with the president of Afghanistan.
Though Trump's top aides emphasized that the administration is examining all diplomatic measures to rein in Pyongyang, they made clear that military options remain on the table.
South Korea urges North Korea to abandon nukes, seek talks
China's foreign ministry said Monday that military threats being made by North Korea and the USA were counterproductive. He previously said the idea should be "deeply considered" by the allies, inflaming already-heated debate on the issue.
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Meanwhile, according to TMZ sources, Travis is also spilling the big news to his buddies that he's going to become a dad. There's about to be a new Kardashian-Jenner in the world-but this time moms Kim or Kourtney aren't involved.
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The backstory here relates to Manafort's finances and long business relationship with Deripaska, the billionaire in question. Manafort spokesman Jason Maloni told Reuters the emails were an attempt by Manafort to collect unpaid debts.
The intermediate-range missile was launched Friday near the isolated nation's capital, Pyongyang, soaring for about 2,300 miles before splashing down in the Pacific Ocean.
The US and South Korea ended a 1950-53 war with North Korea through a truce, not a peace treaty, which effectively leaves the two sides of the conflict technically at war.
During talks Thursday with Prime Minister Shinzo Abe of Japan and President Moon Jae-in of South Korea, Trump was expected to reiterate that military options are available in retaliation for North Korean threats.
He and Trump plan to meet in NY early on Wednesday U.S. time, Moon's office said. It drew a sharp rebuke from the North's Foreign Minister Ri Yong Ho, who said "It would be a dog's dream if he meant to scare us with the sound of a dog barking".
Since its fourth nuclear test a month later, North Korea has conducted two more nuclear tests and flight-tested a slew of new missile systems, including developmental ICBMs that could potentially reach deep into the US mainland when perfected.
Fears of a military confrontation are increasing. It also exploded its most powerful nuclear bomb to date.
The UN sanctions are an attempt to starve North Korea of fuel and income for its weapons programmes, and restrict oil imports and ban textile exports.