Vice President JD Vance is scheduled to lead a team of United States negotiators in Islamabad on Tuesday for talks with Iran aimed at ending their war, even though Tehran is yet to confirm its participation in this latest round of negotiations.

Meanwhile, a fragile two-week ceasefire is poised to expire on Wednesday with no clarity on whether it will be extended amid a spike in tensions over the past two days.

The first round of US-Iran talks in Islamabad on April 11 ended without a breakthrough. Since then, the US has imposed a naval blockade on all Iran-linked ships trying to pass through the Strait of Hormuz. Iran has fired at ships trying to transit through the vital shipping route. And early on Monday, the US shot at and then seized an Iranian vessel trying to pass through the narrow waterway.

Tehran called the ship’s seizure “piracy” and has threatened retribution. It has refused to join talks under the shadow of threats. Trump has revived his warning that he would order the US military to blow up all bridges and power plants in Iran if it does not accept a deal on US terms.

Amid this uncertainty over the future of the talks and the truce, we break down the latest from both sides and four potential scenarios that could play out in the next few days:

What’s the latest from both sides?

Both the US and Iran have been exchanging threats as the ceasefire is due to expire in the coming hours.

The two-week ceasefire, announced by US President Donald Trump on April 7, should expire at 8pm Washington, DC, time on Tuesday (midnight GMT, 3:30am in Tehran and 5am in Islamabad on Wednesday). However, Trump has in recent comments indicated that he has already moved the deadline back by a day.

While Islamabad continues with its preparations to host multiday talks, there has been no confirmation yet from Iranian officials about whether they will attend.

The US president said he feels confident Iran will negotiate or it will “see problems like they’ve never seen before”.

Trump confirmed in a Truth Social post that the US delegation is planning to visit Islamabad on Tuesday. While accusing Iran of violating the ceasefire by firing at vessels in the Strait of Hormuz, Trump added: “We’re offering a very fair and reasonable DEAL, and I hope they take it because, if they don’t, the United States is going to knock out every single Power Plant, and every single Bridge, in Iran. NO MORE MR. NICE GUY!”

Meanwhile, Iran maintained there will be no negotiations under the shadow of threats.

Mohammad Reza Mohseni Sani, who sits on the Iranian parliament’s National Security Commission, cast further doubt on the prospects of talks with the US.

He said in comments carried by Iran’s Mehr news agency that “negotiations are not acceptable” in “the current situation” accusing the US of being “overly demanding” and pursuing ulterior objectives for domestic benefit.

“Given the current conditions, recent aggressions and the history we have with the United States in previous negotiations, the next round of talks is, God willing, off the table,” he said.

Ali Vaez, the Iran project director for the International Crisis Group think tank, told Al Jazeera that the key hurdle before any second round of talks was “whether the US is willing to ease pressure enough to make diplomacy credible and whether Iran is willing to curb its leverage enough to keep talks alive”.

Scenario 1: Talks happen and achieve a temporary deal

Pakistan has been aiming to get the US and Iran to agree to multiple days of negotiations, sources close to the mediation efforts told Al Jazeera.

For the US, Vance is expected to be joined by Trump’s envoy and fellow real estate developer Steve Witkoff and Trump’s son-in-law Jared Kushner, the same team that participated in the first round of talks. If the Iranians come, the parliament’s speaker, Mohammad Bagher Ghalibaf, is again expected to lead their delegation, which will also include Foreign Minister Abbas Araghchi.

Mediators in Islamabad are aiming to reach a “memorandum of understanding” between the US and Iran to buy time to achieve a final deal and extend the ceasefire.

“Success would not be a final deal. It would be an interim understanding that extends talks, stabilises the ceasefire and creates a framework for trading nuclear steps for sanctions relief,” Vaez said.

However, glaring differences exist in the demands and expectations from both sides, including over Tehran’s nuclear programme, control of the Strait of Hormuz, sanctions on Iran and its frozen assets.

“If the two sides do not change their stances, there cannot be a deal in Islamabad,” said Aniseh Bassiri Tabrizi, an associate fellow in the Middle East and North Africa Programme at the Chatham House think tank.

Scenario 2: Talks end without a breakthrough but with a ceasefire extension

For there to be any meaningful progress in the talks, “there needs to be compromises on both sides because at the moment there is too much of a gap to reach an agreement,” Tabrizi told Al Jazeera.

“Unless that changes, it’s unlikely that we will see a deal,” she said.

Trump has doubled down in recent days on his insistence that Iran stop all uranium enrichment and hand over its current stockpile of enriched uranium. Iran has rejected those demands.

“The US is not learning its lessons from experience,” Iranian Ministry of Foreign Affairs spokesman Esmaeil Baghaei said on Monday. “And this will never lead to good results.”

Still, Tabrizi said, even in the absence of a breakthrough in a second round of talks, the two sides may agree to “some sort of temporary extension of the ceasefire”, which would give diplomacy another chance.

Scenario 3: No talks but the ceasefire is extended

Trump told Bloomberg News on Monday that he considers the ceasefire over “Wednesday evening Washington time” and said it was “highly unlikely” that he would extend it if no deal is reached.

Still, a last-minute post on his Truth Social platform extending the ceasefire would not necessarily be surprising, analysts said – even if Iran refuses to show up to the talks in Islamabad.

“It [would be] a fragile pause, not a durable ceasefire,” Vaez said. “As long as maritime pressure and mutual accusations continue, the risk of miscalculation remains very high.”

“Without a diplomatic framework, it would be buying time, not building stability,” he added.

Tabrizi agreed. Already, though, the war has fundamentally changed the US-Iran equation, she said.

“President Trump is arguing that regime change has happened because the figures that they are dealing with are different,” Tabrizi said. “Iran probably doesn’t seem to see the US as an existential threat like before the fighting started.”

Scenario 4: Talks fail, and the ceasefire expires

Trump’s repeated threats to restart the bombing of Iran in the absence of a deal also open up a fourth scenario: If Iranian negotiators do not travel to Islamabad for the talks, that threat will be tested.

“Then lots of bombs start going off,” Trump said to PBS News on Monday when asked about what follows if the ceasefire expires. Trump added that Iran was “supposed to be there” for the negotiations. “We’ll see whether or not it’s there. If they’re not there, that’s fine too,” he said.

Ghalibaf said on Tuesday that Trump “seeks to turn this negotiating table, in his own imagination, into a table of surrender or to justify renewed warmongering”.

“We have prepared to reveal new cards on the battlefield,” he added, suggesting that Tehran was prepared militarily for a resumption of the fighting.

But if the ceasefire collapses, “the next round is likely to get very ugly very quickly,” Vaez warned. “The US will likely target critical infrastructure in Iran, which in turn will torch the rest of the region.”