In this Nov. 10, 2016, file photo, a man reads a newspaper with the headline of "U.S. President-elect Donald Trump delivers a mighty shock to America." Andy Wong/AP Remember when Donald Trump promised to label China a currency manipulator "on Day One"? Whatever happened to that promise?

A review of recent developments in the relationship between the Trump administration and the Chinese is elucidating.

Trump rattled China early on in his administration after taking a phone call from Taiwan's president. It was never clear whether the phone call was a diplomatic blunder or a deliberate strategy.

However, just weeks later, Trump reassured Chinese President Xi Jinping that the United States would support the "One China" policy that sees Taiwan as part of China. Why the abrupt change of heart?

It's worth noting that a few days after that phone call, something else happened: China granted Trump's business a valuable 10-year trademark. The trademark was considered a surprise win for Trump.

Critics have said Trump's business interests create an impossible web of conflicts that could make him vulnerable to undue influence by foreign actors. The China story corroborates those concerns in spades. Consider this: In China, Trump "has 49 pending trademark applications and 77 marks already registered in his own name, most of which will come up for renewal during his term," according to The Associated Press.

"China's decision to award President Trump with a new trademark allowing him to profit from the use of his name is a clear conflict of interest and deeply troubling," said Sen. Dianne Feinstein, Democrat of California, in a statement. "If this isn't a violation of the emoluments clause, I don't know what is.

"The fact that this decision comes just days after a conversation between President Trump and President Xi Jinping where President Trump reaffirmed the US policy of 'One China' is even more disturbing as it gives the obvious impression of a quid pro quo," she added.

The issue initially fell through the cracks because of the uproar over the Trump team's suspicious links to Russia, which was found by US intelligence to have been involved in hacking the American elections.

During the presidential campaign, Trump took an extremely tough tone on China and Mexico, accusing the two US trading partners of stealing US jobs because of what he called "unfair" trade deals and, in China's case, deliberate currency undervaluation. He said he'd respond by hiking tariffs on Chinese goods to an exorbitant 45%, despite warnings of a possible trade war.

Never mind that China has been struggling to prevent its currency from falling too quickly in recent months.

What about China's vicious currency manipulation, which Trump claimed cost American workers millions of jobs? Forget about it.