(CNN) US Ambassador to the United Nations Nikki Haley said she used President Donald Trump's unpredictability to get the Chinese to back tougher international sanctions on North Korea.

"I would always use the unpredictability of President Trump to help me get the sanctions through," Haley told an audience at the University of Houston on Tuesday, recounting conversations with her Chinese counterparts.

"So I would say, 'We have to cut off the (North Korean) laborers', you know? 'We have to do this,'" she recalled. "And they'd say, 'Oh, no, no, we can't do that.'"

"And I would say, 'OK, but I can't promise you that President Trump won't use the military,'" said Haley. " 'I can't promise that there won't be a more forceful action, so why can't we do this and see if we can start to cut the revenue in North Korea?'"

"So it was through that that we did the three sanctions, and by the time I got China to agree to pass those sanctions and I'd get the other countries to agree, then I just told Russia, 'This is getting ready to happen,'" she added. "And we just kind of pushed them out of the way."

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