It’s still several days before Donald Trump’s big summit meeting with Chinese President Xi Jinping, but Trump is already negotiating. The president on Sunday set down a marker about how he wants the two countries to work together, warning that if China won’t cooperate on limiting North Korea’s nuclear ambitions, the U.S. would “solve” the problem on its own.

In an interview with the Financial Times, Trump said that because China holds so much sway over North Korea, it has a duty to help curb the nuclear threat from the secretive kingdom. “China has great influence over North Korea. And China will either decide to help us with North Korea, or they won’t. And if they do, that will be very good for China, and if they don’t, it won’t be good for anyone,” Trump said.

When asked why China should cooperate, Trump returned to his favorite China-related subject. “Trade is the incentive. It is all about trade,” he said. Trump has continuously criticized China’s economic policies and last week introduced a pair of executive orders designed to tackle the issues as he perceives them. Yet Trump’s decisive rhetoric appears to be hiding a state of confusion in the White House, where administration officials struggle to agree on a unified trade policy toward China.

Xi will meet Trump on Thursday at his Mar-a-Lago resort in Florida, which the president refers to as his “Winter White House” — though no golf is expected to be played. With North Korea and economic policy set to dominate the conversation, Trump said last week that the meeting “will be a very difficult one.”

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The U.S. is concerned about the growing threat from North Korea. “There is a real possibility that North Korea will be able to hit the U.S. with a nuclear-armed missile by the end of the first Trump term,” KT McFarland, deputy White House national security adviser, told the Financial Times.

North Korea has ramped up its missile tests in recent months, as tensions grow on the Korean Peninsula. Reports last week suggested the government there could be ready to conduct another nuclear test. North Korea has increased its missile testing in the wake of annual joint U.S.-South Korea military exercises taking place in the region, which the North believes is preparation for an invasion.

North Korea and China haven’t been shy about their disapproval of the U.S.’ decision to begin building its controversial THAAD missile defense system in South Korea.

It’s not clear what Trump meant exactly when he said he would “solve” the North Korean threat. Last month Secretary of State Rex Tillerson, during a visit to the region, said a preemptive strike was an option “on the table,” adding that the “policy of strategic patience has ended.” In February Defense Secretary James Mattis said North Korea’s use of nuclear weapons would be met with an “overwhelming” response.

China is North Korea’s most important trading partner, and without its support Pyongyang would struggle to survive. Trump is looking to make use of that relationship. “What [Trump] is signaling is that the next step is to begin secondary sanctions, which we have avoided,” Dennis Wilder, a former CIA China analyst, told the Financial Times. “They are sanctions on Chinese companies and individuals who deal with North Korea.”

Though China carries influence with the Hermit Kingdom, it hardly controls Pyongyang. China is at much greater risk from nuclear threats from North Korea than the U.S., given North Korea’s current level of missile technology.

According to the New York Times, Trump’s son in law and senior advisor Jared Kushner has been working closely with the Chinese ambassador to Washington, Cui Tiankai, in the lead-up to the meeting. China has sought to woo Trump’s family in recent months, including hosting Kushner and his wife Ivanka Trump during Chinese New Year celebrations.