Once upon a time, a man could write checks his bank account couldn't cover. Since shops and banks wouldn't know for a few days, he had time to live large. And when his scam went sideways, the crook could always skip town and forge some new documents: Find a new bank, and a new set of marks. A con artist could live life this way. But a nation can't. And a superpower really can't.

That's why its more than a little frightening that President Trump, a man who knows bankruptcy law as well as any crook and has done enough bad deals he can't get American banks to finance his ventures, is now in charge of the country's foreign policy.

Right now, the U.S. military has a lot of credit on the world stage. But the way Trump seems ready to write checks on its account should make us nervous. Trump watched a few horrifying cable news segments and now the United States may have a new objective in the Syrian Civil War: the removal of the Bashar Al-Assad's regime.

But unlike your local shopkeepers, the other great powers of the world have an idea of what's in the U.S. account. They know what our navy can do, and how far each model of our airplanes can fly on one tank of gas. They know where we're vulnerable. They can estimate, roughly, what the tolerance for war is among American people.

They know that previous administration bequeathed to Trump some combination of ground troops, special forces, and air operations in six Muslim countries: Afghanistan, Iraq, Libya, Yemen, Syria, and Somalia. And they get the breaking news alerts just like you, showing that Trump seems to be deciding to join the U.S. more directly to more fronts in the Syrian Civil War. Here in America, many commentators interpreted Trump's decision to go after Assad as a sign that America had gotten its swagger back.

But great powers around the world noticed that the U.S. has a tighter monthly budget on power right now and is not in a position to be demanding. A professor of international relations at Fudam University in Shanghai described the feeling in China over this development.

Mr. Shen added that many Chinese were "thrilled" by the attack because it would probably result in the United States becoming further mired in the Middle East.

"If the United States gets trapped in Syria, how can Trump make America great again? As a result, China will be able to achieve its peaceful rise," Mr. Shen said, using a term Beijing employs to characterize its growing power. "Even though we say we oppose the bombing, deep in our hearts we are happy." [The New York Times]

Speaking of China, the U.S. has several priorities near it. We want to keep the trading routes in the South China Sea accessible, and the prosperous city states there as independent as possible. We want to see our allies like South Korea and Japan thrive. And we want China to help contain North Korea, in case its insane ruler threatens our friends. We also probably don't want China to do anything really provocative in Siberia, which it easily could. This week the U.S. is sending ships to the Korean peninsula, to send more messages about the North Korean regime and what will, won't, or can't be tolerated from it.

It's easy to imagine China soon finding itself in a position to ask us to alter one or more of our positions in its neighborhood. The U.S. just has to be distracted by its quest to find the Thomas Jeffersons from Yemen to Libya, and then be met with a crisis. That crisis could be the North Korean regime collapsing from its internal corruption, and South Korea asking for help securing its weapons, or preventing the spillover of people from overwhelming their society overnight.

Even a relatively weakened state like Russia can find itself in more favorable negotiating circumstances with the U.S. merely because of our promiscuity in making promises. Want their help in transitioning Syria away from Assad? Want greater Russian assistance in guaranteeing that Iran sticks to its commitments? Then Nikki Haley may have to stop talking about Crimea and Ukraine.

For some hawks in the U.S., everything is a priority, and backing down anywhere is a sign of lost credibility. But if the United States cannot properly rank priorities, or husband its power, it will find that the value of its commitments can fall in a cascade and reduce to zero very quickly. Our Middle Eastern interventions since 2001 have resulted in few gains and a multiplication of ongoing debits on America's account. America's critical allies and rivals in Europe and in Asia are asking themselves what will be left over for them in the American treasury of power after our Middle Eastern adventures. So should we.