President Donald Trump expressed disappointment about U.S. negotiations with Iran over its nuclear program and warned that “sometimes you have to use force,” amid a massive military presence in the region that could presage strikes on the Islamic Republic.

Trump has increased diplomatic and military pressure on Iran in the weeks since an Iranian crackdown on protesters, attempting to force the country’s rulers to forswear nuclear weapons and other activities Washington sees as destabilizing.

After the latest round of talks on Thursday in Geneva ended without a deal, Trump’s patience appeared to be wearing thin, although he said he had not made a final decision on the use of force.

“They don’t want to say the key words, ‘We’re not going to have a nuclear weapon,'” Trump said on Friday before an event in Corpus Christi, Texas. “So I’m not happy with the negotiation.”

Iran denies it is seeking to develop nuclear weapons and wants any accord to include the lifting of U.S. sanctions against it.

‘PEACE DEAL WITHIN REACH’: ALBUSAIDI

Trump spoke a day after negotiations between U.S. envoys Steve Witkoff and Jared Kushner and Iranian officials in Geneva ended without news of a deal, although Omani Foreign Minister Sayyid Badr Albusaidi, who was a mediator, said the talks made significant progress.

Albusaidi told CBS earlier on Friday, before Trump’s latest remarks, that a “peace deal is within our reach … if we just allow diplomacy the space it needs to get there.”

Iran has agreed in principle that it would never have nuclear material that could be used to create a weapon, Albusaidi said, adding that “if we can capture that and build on it, I think a deal is within our reach.”

A big U.S. military force, including two aircraft carrier groups, is in the region waiting on Trump’s order.

While Trump’s timing for a final decision is unclear, the State Department said Secretary of State Marco Rubio is to hold talks in Israel with Israeli Prime Minister Benjamin Netanyahu on Sunday and Monday.

The United States joined Israel’s bombing campaign against Iran in June, striking major nuclear facilities.

Asked about the potential for use of force, Trump said the United States has the greatest military in the world.

“I’d love not to use it, but sometimes you have to,” he said.

U.S. Secretary of State Marco Rubio said in a statement on Friday that the State Department had designated Iran as a “State Sponsor of Wrongful Detention.”

Rubio said for decades Iran has wrongfully detained Americans and citizens of other nations “to use as political leverage against other states,” adding that the U.S. could consider additional measures, including a potential “geographic travel restriction on the use of U.S. passports to, through, or from Iran.”

Trump planned events in Corpus Christi later on Friday and then was to fly to Palm Beach, Florida, for the weekend at his Mar-a-Lago club.

A source briefed on the internal White House deliberations told Reuters that Trump is “very clear-eyed on all the options before him.”

There is a recognition internally that taking on Iran would be more difficult than the U.S. capture of Venezuelan leader Nicolas Maduro, and there was also internal pessimism as to whether negotiations will bear fruit, the source said.

“Nobody is super optimistic about the negotiations,” the source said.