This column originally appeared on Jan. 27 at 8 a.m. ET on Real Money, our premium site for active traders. Click here to get great columns like this from Jim Cramer and other writers even earlier in the trading day.

As President Donald Trump picks fights with big countries that until a few short weeks ago were in good relations with the U.S., he might want to think about what his measures will do to the U.S. economy itself.

My colleague Alex McMillan made the point that scrapping the Trans-Pacific Partnership will come back to bite America. Also, it doesn't take long to realize that a 20% border tax on imports from Mexico and something similar on imports from China would push already-rising inflation in America through the roof, forcing the Fed to raise rates quicker than it may want.

But perhaps a more worrying consequence is something I have been warning about for a while: a retreat by Chinese capital could crash property markets in developed countries around the world, including the U.S. There are subtle signs that it is beginning to happen to some extent.

Last August, I wrote a story on how China might have been blowing up a global real estate bubble of giant proportions. In November, I warned that China's measures to tighten controls over capital outflows in order to prop up its currency bode ill for real estate, especially in hot spots such as New York, London or Sydney.

That's because when China liberalized the use of its currency abroad, a lot of Chinese investors took advantage and went shopping for property in these cities. That spending spree has contributed to the housing crisis in London, for example, while arguably propping up the property sector and related businesses such as real estate agents and banks.

A story published by Bloomberg overnight shows this wave of Chinese money is about to turn around. Citing anecdotal reports from real estate agents, home owners and developers, the story says the restrictions on Chinese capital inflows already are making life difficult for sellers of high-end real estate in some cities.

A 67-story tower block in London where flats start at a price of £595,000 ($751,000) is such an example. Less than 70% of those who had signed purchase contracts last year paid the initial deposits, and now those who haven't are facing problems as they can get their hands on the funds, the story said, quoting an unidentified official from the project's Shanghai-based developer.

In December, Chinese regulators said the $50,000 a year that Chinese individuals are allowed to exchange into foreign currency must not be used to purchase property abroad. This measure is largely symbolic, as luxury real estate costs far more than $50,000, but another, more worrying piece of news came out yesterday.

The South China Morning Post, a Chinese newspaper, reported that China is taking steps to reverse the flow of capital abroad by allowing the repatriation of offshore loans backed by domestic guarantees. The paper also said multinationals are now allowed to tap 100% of their foreign currency deposits abroad to invest domestically, up from a 50% cap previously.

It is hard to quantify how many Chinese companies used the freedom granted by regulators in 2013 to lend money to their subsidiaries abroad without any limit to buy foreign property. However, it is undeniable that real estate prices in hot spots around the world have posted strong increases since then.

Chinese investors made up 26.7% in dollar terms of all foreign buyers of U.S. property, investing around $27 billion in the asset class from April 2015 to March 2016, according to data from the National Association of Realtors. California tops the geographical preferences of Chinese buyers, with 32% of them buying there. It is followed by New York, preferred by 10% of buyers.

What does all this have to do with Trump's tough stance on China? More than a lot of people think. Trump repeatedly has accused China of manipulating its currency to keep it weak in order to make its exports more competitive, hurting the U.S. He has threatened retaliatory measures such as import tariffs.

However, if anything, China is making desperate attempts to strengthen, not weaken, its currency. If Trump doesn't lay off the criticism, he risks forcing China to accelerate its efforts to tighten capital controls (he probably already did, to some extent). This situation could lead to asset sales in the property markets in global hot spots, including New York.

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