President Donald Trump has issued an extraordinary threat to bomb Oman—a longtime American security partner that has spent months attempting to mediate an end to his war with Iran.

“If Oman gets in the way, we’ll bomb the s—t out of them,” Trump declared Monday during an interview with Fox News.

The threat immediately stunned observers because Oman is not an enemy of the United States. The Gulf nation has historically maintained close relations with Washington while using its unusual access to Tehran to facilitate sensitive diplomatic negotiations.

Since Trump’s war with Iran began in February, Oman has served as an essential backchannel between the two combatants.

Now the very country attempting to prevent further escalation could find itself threatened with American bombs.

At the center of the confrontation is the Strait of Hormuz, one of the most strategically important waterways on Earth. Approximately one-fifth of global oil and gas supplies normally pass through the narrow passage during peacetime.

Iran has kept the strait closed since the first bombs fell, severely reducing shipping traffic, disrupting energy supplies and contributing to higher gasoline prices.

The resulting economic pain has intensified political pressure on Trump at home, where public support for the war—and for his presidency—has reportedly deteriorated.

Iran says it has been working with Oman on a plan to reopen the waterway. But Oman’s discussions about potentially regulating traffic through the strait appear to have enraged Trump, who insists that no regional government will control it.

“Nobody is going to control it,” Trump warned during a May Cabinet meeting.

“It’s international waters, and Oman will behave just like everybody else, or we will have to blow them up.”

The legal and geographic reality is more complicated.

The Strait of Hormuz is recognized as an international strait open to international navigation, but much of the narrow passage lies within the territorial waters of Iran and Oman.

That means reopening it safely may require precisely the kind of regional coordination Oman has reportedly been pursuing.

Trump appears to regard any Omani attempt to influence shipping arrangements as interference with American military objectives.

His latest threat arrived as an ambitious deadline for resolving the conflict expired without a broader peace agreement.

Trump previously signed a peace memorandum at Versailles that envisioned a comprehensive deal within 60 days. Monday marked the end of that period, yet the United States and Iran remained far from a final settlement.

The diplomatic failure has left the administration increasingly dependent on military force.

American naval assets led by the USS Abraham Lincoln have attempted to restore traffic through the strait. Trump has claimed the United States achieved “total control,” but available shipping data tells a dramatically different story.

“Traffic has slowed really to a trickle,” Fox News anchor Bret Baier said last week.

Before the conflict, more than 100 vessels crossed the strait each day, according to Baier. On one recent Monday, only eight passed through. The following day, the number increased to just 14.

The stalled shipping lanes are not the only crisis confronting the president.

The USS Abraham Lincoln and its crew are now enduring a ninth month of deployment. Family members have described deteriorating conditions aboard the aircraft carrier, while reports suggest some desperate sailors have attempted to jump overboard.

Those accounts have transformed the ship from a symbol of American military strength into a source of mounting political pressure.

Questions are also growing over the rate at which the United States is consuming missiles and other weapons.

Critics fear that maintaining the Iran campaign could drain stockpiles needed to deter or confront future threats elsewhere in the world.

Asked about those concerns during the Fox News interview, Trump dismissed them.

“What we’ve used is peanuts,” he said. “We have a lot of mid-level weapons.”

An analysis from the Center for Strategic and International Studies concluded that the United States has enough munitions to sustain the current war under projected circumstances. However, it also warned that prolonged consumption could create dangerous shortages during later conflicts.

That distinction matters.

America may possess enough weapons to continue bombing Iran. The harder question is whether doing so leaves the country prepared for another crisis involving China, Russia, North Korea or another adversary.

Now Trump has added Oman—a nation that has assisted the United States and attempted to mediate peace—to the list of countries facing his military threats.

The president may intend his language as coercive diplomacy designed to prevent interference in the Strait of Hormuz. But publicly threatening to destroy an ally risks undermining the trust necessary to end the war.

Oman has been one of the few doors connecting Washington and Tehran.

Trump just threatened to blow that door apart.