President Donald Trump on Monday announced that the United States and Iran will begin direct, high-level talks starting Saturday, amid rising nuclear tensions. Trump warned that if no agreement is reached, Tehran will be in “great danger” as it cannot be allowed to develop a nuclear weapon.

While Trump did not disclose the location or names of participants, he stated repeatedly during a joint news conference with visiting Israeli Prime Minister Benjamin Netanyahu that the talks would occur at “almost the top level” and are of “very high importance”.

The announcement follows Trump’s earlier public offer for dialogue, which had been rejected by Iran’s Supreme Leader Ayatollah Ali Khamenei. Despite this, Trump confirmed the meeting will proceed.

“We are having direct talks with Iran,” Trump said. “We have a very big meeting, and we’ll see what can happen. I think everyone agrees that doing a deal is better than the alternative. And the alternative is not something I want to be involved with—or that Israel wants either, if they can avoid it.”

The president’s reference to “the alternative” was widely interpreted as a military option.

Trump has maintained a maximum pressure policy on Iran, especially after withdrawing from the 2015 Iran nuclear deal (JCPOA) during his first term. That agreement, brokered by President Barack Obama and six global powers, had offered sanctions relief in return for Tehran limiting its nuclear activities.

“If the talks aren’t successful,” Trump warned, “Iran will be in great danger. They cannot have a nuclear weapon. It’s not complicated. That’s the bottom line.”

In a notable aside, Trump also suggested that some existing nuclear powers “should not have” nuclear weapons, though he did not specify which nations. There are currently nine nuclear-armed states: the US, Russia, China, France, UK, India, Pakistan, Israel, and North Korea.

The upcoming talks could mark a turning point in US-Iran relations, depending on the outcome and scope of the negotiations.