WASHINGTON - The White House is ratcheting up the urgency over North Korea's nuclear pursuit ahead of U.S. President Donald Trump and President Xi Jinping's first meeting, with a senior U.S. official warning that the "clock has now run out" on Pyongyang.

Trump and Xi will huddle Thursday and Friday at Trump's Mar-a-Lago estate in Florida, a venue chosen to give the summit a more informal feel. White House officials said Tuesday that trade and security would be high on the new American president's agenda, including pushing China to exert more economic pressure on North Korea.

Speaking at a White House business forum Tuesday, Trump called North Korea a "humanity problem." A White House official later said "all options are on the table" for the U.S., though the official would not say what steps Trump was willing to take to curb Pyongyang's pursuit of a nuclear weapon.

North Korea fired a ballistic missile into the waters off its east coast on Wednesday, U.S. and South Korean officials said, in a reminder of the simmering tensions on the Korean peninsula.

Like many nations, China is still grappling with Trump's mercurial nature after the relative transparency and predictability of the bilateral relationship under Barack Obama. Both during his campaign and after his victory, Trump complained repeatedly over China's allegedly unfair trade practices, its perceived lack of assistance in reining in North Korea and its drive to cement control over the South China Sea.

Some analysts believe Xi might be willing to hand Trump a symbolic victory on trade to put a positive spin on the meeting.

"Xi probably can't accommodate Trump on sovereignty and security issues, but he has a lot of leeway on economics," said Robert Sutter, a China expert at George Washington University in Washington, D.C.

Yet even if Xi is able to offer Trump deliverables, he will still have to deal with "a restless U.S. president valuing unpredictability and seeking advantage for his agenda going forward," Sutter said.

Trump was seen as moving trade even more to the forefront when he signed a pair of executive orders Friday focused on reducing the trade deficit. Coupled together, the orders appeared to be a symbolic shot at China, which accounted for the vast bulk - $347 billion - of last year's $502 billion trade deficit.

While aides insisted the timing was coincidental, the administration touted the moves as evidence of it taking an aggressive but analytical approach to closing a trade gap that is largely due to the influx of goods from China.

Still, Trump told the Financial Times newspaper that during his meeting with Xi, he doesn't "want to talk about tariffs yet, perhaps the next time we meet." A second White House official said Tuesday that the topic may come up, though there was not expected to be any resolution.

The officials would only discuss the upcoming summit on the condition of anonymity in order to avoid pre-empting the president.

Looming over the visit will be North Korea's nuclear provocations. China continues to oppose the tough measures demanded of it to address the issue, fearing a collapse of the Pyongyang regime would bring a crush of refugees and possibly U.S. and South Korean troops on its border.

Trump told the Financial Times the U.S. is prepared to act alone if China does not take a tougher stand against North Korea's nuclear program.

"China has great influence over North Korea," Trump said. "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."

Add to the mix the issue of the South China Sea, where China has built and armed man-made islands despite the concerns of neighbouring countries; and Taiwan, the self-governing island democracy that China claims as its own territory, and that some in Trump's administration would like to build a stronger relationship with.

Despite such divisions, Beijing seems committed to establishing a positive relationship between the two leaders.

"It is fundamental for them to improve understanding between each other," said Xiong Zhiyong, a professor at Peking University's School of International Relations. "Both sides have shown their willingness to co-operate and they are expected to make a commitment for co-operation."

China, Xiong said, realizes that Trump "is a leader with a strong personality."

The White House said Trump and Xi would hold meetings and a dinner on Thursday, then gather again Friday for more discussions and a working lunch. First lady Melania Trump and Xi's wife, famed songstress Peng Liyuan, plan to attend the dinner.

As personalities, Xi and Trump are a study in contrasts. A lifelong Communist Party apparatchik and son of a former vice-premier, Xi has built his career with a cautious approach, avoiding controversial reforms and rarely speaking out in ways that would distract from his core message. His nearly five years as head of the ruling party have been defined by a campaign to achieve the "Chinese dream" of increasing prosperity while tackling endemic corruption.

Still, outwardly cordial relations with U.S. presidents are also a longstanding Chinese tradition, in recognition of the importance of the relationship. Xi had taken pains to appear at ease in the company of Obama, avoiding the rancour that characterized the relationship between the American leader and Russian President Vladimir Putin.

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Associated Press writer Vivian Salama contributed to this report from Washington.