CAIRO, Feb. 15 (Xinhua) -- Iranian Foreign Minister Seyed Abbas Araghchi headed to Geneva on Sunday for a second round of Tehran-Washington indirect talks, even as relevant parties laid out starkly different visions of what a deal should entail, exposing the fragile foundations of the renewed diplomatic push.

Araghchi is leading a "diplomatic and specialized" delegation to the talks on Tuesday. He is expected to meet Swiss Foreign Minister Ignazio Cassis, Omani Foreign Minister Sayyid Badr bin Hamad Al Busaidi, and Rafael Grossi, director general of the International Atomic Energy Agency, among other officials, according to a ministry statement.

U.S. President Donald Trump's special envoy Steve Witkoff will lead the American team, according to media reports.

The meeting follows the first round in Oman's Muscat on Feb. 6 that both sides described as a "good start" but yielded no visible breakthrough.

In public statements ahead of the Geneva meeting, Iranian officials struck a tone of conditional openness mixed with defiance. Speaking to BBC on Sunday, Iran's Deputy Foreign Minister Majid Takht-Ravanchi signaled Tehran's willingness to compromise on its nuclear program in exchange for sanctions relief, but drew firm red lines.

"The ball is in America's court to prove that they want to do a deal," Takht-Ravanchi said.

He confirmed that Iran could discuss diluting its 60 percent-enriched uranium as the country's proof of flexibility, but flatly ruled out zero enrichment on Iranian soil.

"It is not on the table anymore," Takht-Ravanchi said, reiterating that Iran's missile program is non-negotiable.

Hamid Ghanbari, a deputy foreign minister for economic diplomacy and a member of Iran's negotiating team, revealed that past discussions in Muscat explored joint investment in energy and mining projects and the potential purchase of U.S.-made aircraft, according to Iran's semi-official Fars news agency.

Any agreement, Ghanbari stressed, must ensure the release of Iran's frozen assets abroad in a "real and usable" manner.

He further stated that while Tehran is seeking a "serious agreement," it will not accept zero uranium enrichment.

According to Iran's official IRNA news agency, Iran's armed forces chief of staff, Abdolrahim Mousavi, warned Sunday that any war would carry consequences for the United States.

"If Trump seeks war with Iran, why does he speak of negotiation?" Mousavi said, adding that entering a conflict would "teach him a lesson" and end his "blustering."

Meanwhile, signals are similarly mixed from Washington. U.S. Secretary of State Marco Rubio said Trump prefers diplomacy and a negotiated settlement. "No one's ever been able to do a successful deal with Iran, but we're going to try," Rubio said at a news conference in Bratislava, the capital of Slovakia.

Israeli Prime Minister Benjamin Netanyahu, following his meeting with Trump in Washington, also suggested that Trump is "determined to exhaust the possibilities of achieving a deal, which he believes can be achieved now."

But Trump himself has kept military options open. He told reporters on Thursday that if negotiations with Iran fail, "we'll have to go to phase two. Phase two will be very tough for them."

On Friday, Trump said the USS Gerald R. Ford, the world's largest aircraft carrier, had been ordered to join the USS Abraham Lincoln and three guided-missile destroyers already deployed to the Middle East region.

The tensions seem to run even deeper behind the scenes. CBS News reported Sunday that Trump told Netanyahu as early as December that he would support Israeli strikes on Iran's ballistic missile program if a deal cannot be reached.

CBS News said U.S. officials have since begun internal discussions on how to assist such an operation, "including the provision of aerial refueling for Israeli aircraft and the delicate matter of securing overflight permission from countries along the potential route."

Netanyahu, for his part, has set a maximalist bar. Speaking at a public conference on Sunday, he insisted that any potential agreement with Iran must include the removal of nuclear material, a halt to uranium enrichment and restrictions on ballistic missiles.

Netanyahu also reiterated his skepticism "about any deal with Iran."

With U.S. warships massing in the region and both sides preparing for the possibility of failure, it is widely believed that the upcoming talks on Tuesday may test whether diplomacy can still offer a path forward, or merely serve as a prelude to deeper confrontation.