As Iran girds for possible war with the United States, President Trump may turn out to be the best friend it has.

Despite the saber-rattling of senior aides and Trump’s own tweets, when push has come to shove over the past two years, the president has repeatedly backed away from the threatened use of military force.

Whether the target has been North Korea, with which warnings of “fire and fury” have become little more than an exchange of “beautiful” letters between Trump and Kim Jong Un, or Venezuela, where the threat of “all options” has failed to upset the status quo, the president has blinked. With Iran, the dispatch of a U.S. aircraft carrier and a bomber task force, as well as reported plans to deploy 120,000 troops, were quickly followed by Trump’s insistence that he only wants to talk to Iranian leaders.

Trump has said that there is no inconsistency in his administration’s messaging but that the image of incoherence can be useful. “At least Iran doesn’t know what to think, which at this point may very well be a good thing!” he tweeted Friday.

But as he moves more deeply into the second half of his term with major foreign policy issues unresolved, Trump’s credibility has suffered, and his options have narrowed.

“If you make threats and then people decide you aren’t going to follow through, if you’re looking for the reaction and you stop getting the reaction, the options are either to make larger threats or to stop going down that road at all,” said Jon B. Alterman, Middle East Program director at the Center for Strategic and International Studies.

“Credibility is a hard thing for a president to maintain,” Alterman said.

[For inured foreign officials, the sting of Trump’s tweets has begun to dull]

Iran, which has said that it doesn’t want war but is ready for it, has responded with its own taunts and bellicose rhetoric.

“With the B Team doing one thing & @realDonaldTrump saying another thing, it is apparently the U.S. that ‘doesn’t know what to think,’ ” Foreign Minister Mohammad Javad Zarif tweeted Friday in response to Trump. Zarif frequently refers to White House national security adviser John Bolton as the head of the “B team,” or simply, “the Moustache.”

“We in Iran have actually known what to think for millennia — and about the U.S., since 1953. At this point, that is certainly ‘a good thing!’ ” Zarif wrote. In 1953, the CIA orchestrated the overthrow of an elected leftist government in Tehran, bolstering the U.S.-backed monarchy that itself was ousted in 1979 by Iran’s current clerical rulers.

The administration sees Iran as now in the grip of devastating sanctions, its oil income effectively cut off, and close to economic and political collapse. But Iran is fortified by the success of its recent efforts to expand its power across Iraq, Syria and Lebanon. If its own messaging is to be believed, it perceives declining American influence across the Middle East, as Trump seeks to withdraw and regional powers seek closer relations with other world powers, notably Russia and China.

“The Americans are unwilling and unable to carry out military action against us . . . and their unwillingness stems from their inability,” Brig. Gen. Hossein Dehghan, a military aide to Supreme Leader Ali Khamenei, said last week, according to the Iranian Fars News Agency.

Trump has clearly made good on his campaign promises to cancel international agreements, wreak havoc on what he has called “unfair” trade agreements, and repair tattered U.S. relations with Israel and Saudi Arabia. But his desire to pull back from costly wars and avoid new ones has often seemed at odds with the bombastic rhetoric that comes from him and his aides — principally Bolton and Secretary of State Mike Pompeo — and has forced both allies and adversaries to divine which of Trump’s instincts will prevail.

That has been particularly problematic in the case of Iran. The administration last week sent an aircraft carrier and bombers to the Persian Gulf in response to what it has said is intelligence indicating that Iran and its proxies in the region are preparing attacks on U.S. forces and their allies.

[John Bolton puts his singular stamp on Trump’s National Security Council]

Few in the region doubt that Iran was behind the sabotage that blew holes in the hulls of two Saudi tankers and a Norwegian ship in the Persian Gulf on Sunday. But “it was very well designed not to justify a violent reaction,” said Sami Nader, director of the Levant Institute for Strategic Affairs in Beirut. “The objective was to test American resolve to use power.”

“They calculate [Trump] will not risk a protracted or full-scale war,” Nader said. “We will see more incidents, and they could spin out of control.”

European allies, who agree with the administration’s assessment of Iran’s expansionist aims but are still smarting from Trump’s withdrawal from the Iran nuclear deal last year, have been skeptical of the intelligence and worry about the possibility of miscalculation. “I personally believe the American president doesn’t want to go to war. But that’s not the problem,” said a senior European diplomat whose government was briefed by Pompeo this week. “The problem is that the situation may at some point become so volatile and so unstable that it’s inevitable.”

Republican lawmakers have complained that the administration has not briefed them on its justification for the deployment, while Democrats have suggested the intelligence may have been exaggerated to justify an attack on Iran long advocated by Bolton.

“As we try to make sense of the raised tensions in the Persian Gulf, we should not forget that sixteen years ago, the United States went to war in Iraq on the basis of distorted and misrepresented intelligence,” Rep. Eliot L. Engel (D-N.Y.) said in a statement Wednesday. “That must never be allowed to happen again.”

In a briefing Thursday for a small group of journalists, senior administration officials offered a convoluted explanation, saying that their goal was not to start a war but to deter Iran from taking action in response to the intensifying pressure of U.S. sanctions.

Trump has expressed frustration with Bolton, joking to him and other aides that “we’d be in war everywhere if it was up to this guy,” according to a senior administration official who has heard the comments. Trump has often told advisers that he doesn’t want to send a single additional troop anywhere.

He has allowed Bolton, who issued the initial White House statement announcing warships were on their way, to take the lead in threatening Tehran. Just days later, Trump told reporters that Iran had “great potential.” Like North Korea, he said, Iran’s leaders should be “calling me up, sitting down,” so that “we can make a deal.”

Asked Thursday if the two countries were headed toward war, Trump said: “I hope not.”

As concern over escalating tensions with Iran has risen this month, the president has sharply denied any daylight between him and Bolton. Media accounts of “infighting with respect to my strong policy in the Middle East” are “Fake News,” he tweeted this week. “Different opinions are expressed and I make a decisive and final decision — it is a very simple process.”

Privately, Trump is dismissive of turmoil in the Middle East, telling White House officials and informal advisers that nothing good comes from being involved.

As he has repeatedly described it, his goal is to have a “tough” and “strong” military that doesn’t have to do anything — and to use rhetoric that scares people. In a 70-minute meeting Wednesday with surrogates who often appear on television to back him, Trump concentrated on China and immigration. He never mentioned Iran.

Rep. Peter T. King, a New York Republican and Trump ally, said there was a plan behind the seeming confusion. “His strategy is to shake things up with Iran and also say he doesn’t want to go to war,” King said. Trump, King said Friday, is “a good cop and a bad cop. We’ll see if it works. I don’t think we’ll end up going to war.”

The president, he added, “is verbally aggressive and loves sanctions. . . . It could cause them to be more conciliatory. It might not work, but I think people shouldn’t prejudge it. We’ll see in a year.”

Sly reported from Beirut.