In this Sunday, July 21, 2019 file photo, President Donald Trump walks on the tarmac to board Air Force One at Morristown Municipal Airport, in Morristown, N.J. Iran said Monday that it has arrested 17 Iranian nationals allegedly recruited by the Central Intelligence Agency to spy on the country's nuclear and military sites, and some of them have already been sentenced to death. Trump tweeted that the claim had "zero truth," calling Iran a "total mess." Credit: Manuel Balce Ceneta | AP

“Totally false,” Donald Trump tweeted about the Iranian government’s claim of arresting 17 people for spying for the Central Intelligence Agency.

Trump, for once, is most likely right. There is little hard evidence to back up Iran’s claim. It is probably just another tactic in the escalating war of words and threats between this administration and Iran.

Furthermore, since the 1979 Iranian revolution and break in U.S.-Iran relations, American intelligence agencies have few if any ears and eyes on the ground in that country.

But this incident only highlights one of the most terrible — and costly — truths about Trump, his character, judgment, in fact, his entire presidency: Why should anyone believe him?

Trump has made false or misleading claims and comments 10,796 times since his inauguration, according to the Washington Post Fact Checker. From his documented ties to Russia to the border wall, on issues ranging from grave national security matters to his alleged sexual relations with porn stars and Playboy models, the president has shown time and again that he has not a shred of credibility.

Trump, a New York Times White House correspondent wrote recently, “has spun out so many misleading or untrue statements about himself, his enemies, his policies, his family, his personal story, his finances …that even his former communications director said ‘he’s a liar.’”

It is not only sad, but also extremely injurious to our national health and to our standing in the world.

There is reason to get tough on Iran. Iranian leaders are responsible for the deaths of hundreds of American soldiers during the war in Iraq. Their agents are considered responsible for the bombing of the U.S. Marine barracks in Beiru t in 1983, which killed 240 Marines. Today, their proxies continue to exploit tensions across the Middle East.

The problem is that Trump has a very weak, second-rate national security team after getting rid of the first White House group because they didn’t agree with him — with one reportedly calling him a “moron,” and another saying that he has the mind of a “fifth- or sixth-grader.”

As a result, combined with his total lack of credibility, the president has no real or long-term strategy for dealing with Iran. That has been painfully clear since he withdrew from the 2015 nuclear accord reached with Iran by President Barack Obama and China, Germany, France, Russia and Britain — who all still support the deal.

While constantly threatening fire and fury against Iran and its rulers, he has done nothing but back himself into a corner: not wanting war, supposedly, but unable to get Tehran’s leaders to agree to negotiate because he issued an ultimatum — a list of 12 demands, that no leader anywhere would accept.

Consequently, the Trump administration has allowed a mid-rank power, one that previously agreed not to pursue nuclear capability, to threaten to resume nuclear research, to endanger a crucial oil shipment route, and to gain the upper hand in a very dangerous confrontation.

In today’s high-risk crisis, without credibility from many allies, Trump is not even respected by the Iranians, who do not seem to believe him when he threatens them. He has succeeded in isolating the U.S., not Iran.

If Trump had any sense of strategy, he could have doubled down on the 2015 nuclear agreement instead of withdrawing from it. Without increasing sanctions lifted under the accord, he could have demanded an end to provocative actions by Iranian proxies and curtailment of ballistic missile tests that continued. He could have intensified criticism of Iran’s terrible human rights record.

One knowledgeable observer recently suggested a bold way for Trump to get himself and the United States out of a no-win position on Iran and its nuclear ambitions. Reese Erlich suggested a four-part stratagem: fire war-hawks like Secretary of State Mike Pompeo and National Security Adviser John Bolton, declare his “maximum pressure” campaign against Iran a great victory given clear damage to Iran’s economy and oil exports, rejoin the 2015 nuclear agreement along with lifting sanctions, and sit down with Iran’s president to sort things out and seek a grand bargain. Though he’s thus far accomplished nothing but ‘photo ops,’ that is virtually the same approach Trump has taken with North Korea, a country that already has a nuclear arsenal.

Frederic B. Hill, a former foreign correspondent for The Baltimore Sun, conducted wargaming exercises on national security issues for the Department of State.