North Korean leader Kim Jong Un, left, and President Trump. (ED JONES/SAUL LOEB/Agence France-Presse/Getty Images)

President Trump’s braggadocio, ignorance and dishonesty make it virtually impossible to run a mature, coherent foreign policy. He tosses around phrases as if this were a video game. (“Military solutions are now fully in place, locked and loaded, should North Korea act unwisely. Hopefully Kim Jong Un will find another path!” What that actually means is unclear.) He misrepresents the state of our military readiness.

On his claim he refurbished America’s nuclear arsenal, Posts fact-checker Glenn Kessler finds, “Trump indeed gave an order to launch [a Nuclear Posture Review], but that is standard procedure for a new administration. But he’s kidding himself — or misleading Americans — that much has changed in the nuclear arsenal since he took office in January.” And when he says something stupid or conveys weakness, as he did with thanking Russian President Vladimir Putin for kicking out our diplomats, he uses the same phony excuse: Just kidding! (Not only did he at the time evince no sign of humor, but “sarcasm” makes no sense in this context. Instead of rebuking our foe he made a joke? That’s a shoddy non-excuse.)

This stream of nonsensical rhetoric has serious consequences. Our allies and foes can never tell if he is engaging in hollow puffery, if he’s uninformed, or if he’s lying or joking. And if he ever is called upon to justify what really is an imminent threat, who’s going to believe him? That’s a serious problem for the president and for the United States. German Chancellor Angela Merkel for one has had enough. Today she publicly rebuked Trump:

“I don’t envision a military solution to this conflict but rather consistent work as we’ve observed at the United Nations Security Council,” Merkel told reporters.

“Germany will very intensively take part in the options for resolution that are not military, but I consider a verbal escalation to be the wrong response,” she said when asked about Trump’s latest tweets on North Korea.

Merkel called for “very close cooperation” to defuse tensions in the region “particularly by the United States and China but also South Korea and Japan.”

The German government had earlier this week urged both Washington and the nuclear-armed regime in Pyongyang to show “restraint” after they lobbed apocalyptic threats at each other in a mounting war of words.

Our foes see that we are out of sync with our closest allies and that Trump is out of sync with other senior national security advisers. This weakens the president in dealing not only with North Korea but also with China, Iran and other threats to our national security. Trump’s words don’t increase his stature or scare foes; they induce disdain and ridicule while scaring our allies.

When the United States is not reliable, other powers look elsewhere for stability. In this case it is China that benefits from Trump’s diminished credibility. According to China-watchers, China is more than happy to “watch Mr. Trump’s credibility falter among American allies and adversaries alike.”

And since Trump likes to brag about the stock market so much, it is worth noting that his undisciplined rhetoric is spooking the markets. The New York Times reports: “A sell-off in global markets accelerated on Friday as tensions between the United States and North Korea escalated, driving investors toward havens. Asian stock markets closed lower and European indexes opened sharply down on fears that the verbal back-and-forth between Washington and Pyongyang had raised the risk of actual conflict.”

Unfortunately, no one in this administration has the ability to convince the president that his showboating, reality TV-style, is bad for America’s prestige, alliances and nerves. It also happens to be bad for business.