Hong Kong (CNN) When it comes to China, has US President Donald Trump played a diplomatic master stroke?

Not so fast, say analysts who are quick to puncture hopes of budding bromance between the leaders of the two countries.

On Wednesday, Trump said China had made a "big step" towards cracking down on its unruly ally, North Korea, by turning back a fleet of coal-carrying cargo ships from its shores.

Trump's statement came days after he met with Chinese President Xi Jinping at Trump's Mar-a-Lago resort. The two then spoke Tuesday in what the White House called a "very productive" phone call.

"The vast amount of coal that comes out of North Korea going to China, they've turned back the boats. That's a big step, and they have many other steps that I know about," Trump said at a news conference Wednesday.

"We have a very big problem in North Korea. And, as I said, I really think that China is going to try very hard, and has already started." Trump said Xi "wants to do the right thing."

And in another potential sign of closer co-operation with Washington, China, which has vetoed six resolutions on Syria since the civil war began , abstained at a UN vote to condemn Syria over the recent chemical attack in Idlib province.

JUST WATCHED China cuts coal imports from North Korea Replay More Videos ... MUST WATCH China cuts coal imports from North Korea 01:45

Has China really budged?

Trump's fulsome praise for his Chinese counterpart is premature, says Anthony Ruggiero, a senior fellow at the Washington-based Foundation for Defense of Democracies. He says Beijing is only making good on past promises -- including two UN resolutions China agreed to last year.

"Trump is taking credit for their (China's) new robust sanctions but this is something that China should have been implementing last year," said Ruggiero, a former government official who has advised the US on North Korea. "It's ridiculous."

Coal is North Korea's biggest export and a major source of foreign currency for Kim Jong Un's regime, which has stepped up its missile and nuclear development program since 2016.

While CNN has not independently confirmed reports of China refusing North Korean coal ships, Huang Songping, a Chinese customs spokesman, said Thursday that China hadn't imported any coal from North Korea since February 18.

However, the overall trade volume between both countries actually went up 37.4% in the first quarter of 2017, according to Chinese customs officials.

Ashley Townshend, a research fellow at the United States Studies Centre at the University of Sydney, says while the coal import ban is useful, it's not going to stop North Korea firing off missiles or conducting another nuclear test -- something US officials believe is imminent.

"It's highly visible but not necessarily a lasting victory," he said.

JUST WATCHED What might Trump's Syrian attack mean for China? Replay More Videos ... MUST WATCH What might Trump's Syrian attack mean for China? 05:29

Benefits to unpredictability

Ruggiero argues that if Trump is serious about getting China to cut off its support for North Korea, it needs to go after Chinese banks and companies -- something that China is much more likely to object to as it has no interest in pushing sanctions that would force Kim's regime to collapse.

He says Chinese bank accounts are used to conduct business with North Korea and the US should force Chinese banks, many of which have multinational operations, to choose between aiding North Korea and accessing the US banking system.

That said, analysts argue that Trump's unpredictability has unsettled China -- although it's unclear whether it has been a strategic ploy to shake up the bilateral relationship and gain leverage or simply a result of circumstance.

Trump's strike on Syria, which took place while he dined with Xi at Mar-a-Lago , gave China proof that Trump isn't afraid to take military action unilaterally, says Zhang Baohui, a professor at Lingnan University in Hong Kong, who focuses on Chinese politics and international relations.

"China is genuinely concerned that the US may pre-emptively strike against North Korea," he said.

And these fears have been heightened by the US decision to send an aircraft carrier strike group to waters off the Korean peninsula, he added -- something Trump has described as an "armada."

JUST WATCHED Trump: 'Armada' heading toward North Korea Replay More Videos ... MUST WATCH Trump: 'Armada' heading toward North Korea 00:32

So what's in it for China?

Matt Rivers, CNN's Beijing correspondent, says February's coal ban, and subsequent return of coal-laden ships to North Korean shores, accomplishes two things for China.

First, it allows China to show the international community that it is willing to comply with sanctions. Secondly, it gives them a clear rebuttal to the Trump administration's argument that China isn't doing its part to rein in its unpredictable neighbor.

That could lead to greater leverage in future negotiations on other issues like trade -- something that could be behind Trump's decision not to follow through on a campaign trail threat to label China a "currency manipulator."

Xi is maneuvering ahead of the next Communist Party Congress in the fall, that he hopes to use to solidify his power for his second five-year term, and a trade war is something he would want to avoid.

The confrontational rhetoric Trump used against China on the campaign trail and as president-elect has largely come to nothing -- prompting some to suggest that Trump is a 'paper tiger ' with no coherent world view. But Ruggiero says Trump's approach may yet pay off.

"All the issues are in the basket and he's (Trump) playing them off one against the other," says Ruggiero. "Certainly, it seems he pressed hard at least for the abstention in the Security Council," he said.

"In the end, he's a dealmaker. It's a complicated relationship and maybe that's the approach you need."