The United States expressed confidence that peace talks with Iran would go ahead in Pakistan and a senior Iranian official said Tehran was considering joining, but significant hurdles and uncertainty remained ​as the end of a ceasefire approached.

US President Donald Trump wants an agreement that would prevent further oil price rises and stock markets shocks but has insisted Iran cannot have the ‌means to develop a nuclear weapon. Tehran hopes to leverage its control of the Strait of Hormuz to strike a deal that averts a restart of the war, eases sanctions but does not impede its nuclear program.

The Iranian official, speaking to Reuters, said Tehran was “positively reviewing” its participation in talks, despite earlier ruling them out, but stressed no decision had been made.

Officials in Islamabad caution that the situation remains fluid amid heated rhetoric from both Washington and Tehran. According to people familiar with the plans, Vice President Vance is expected to depart Washington on Tuesday.

Read: Pakistan steps up efforts to salvage talks

The second round of negotiations is tentatively scheduled for Wednesday (tomorrow), they said, although the White House has not formally confirmed the timing but has indicated that the delegation is expected to travel soon.

“Things are moving forward, and the talks are on track for tomorrow,” the source said on Tuesday on the condition of anonymity.

Iranian Foreign Ministry condemns US seizure of cargo ship in Gulf of Oman

Iran’s Foreign Ministry on Tuesday condemned the recent seizure by US forces of a cargo ship allegedly attempting to evade a blockade on Iranian ports.

“The Ministry of Foreign Affairs of the Islamic Republic of Iran strongly condemns the unlawful and violent action of the US ‘terrorist army’ in attacking the Iranian commercial vessel ‘Touska,’ which took place on Sunday,” the ministry said in a statement.

Calling the incident a “form of maritime piracy and a terrorist act,” the statement said it violated international law, as well as a two-week ceasefire with the US that began on April 7.

It demanded the release of the Iranian-flagged vessel as well as its crew and their families.

“Without doubt, the Islamic Republic of Iran will use all its capacities to defend its national interests and security, and to safeguard the rights and dignity of Iranians,” it said, asserting that responsibility for “further escalation” would rest with the US.

The US Central Command (CENTCOM) announced Sunday that US naval forces seized the Iranian-flagged cargo ship TOUSKA in the Gulf of Oman after it reportedly refused to comply with blockade directions.

CENTCOM said on Monday that American forces have directed 27 commercial vessels to turn around or return to an Iranian port since the naval blockade of Iranian ports began on April 13.

Oil price down on talks optimism

Oil prices ​fell, and stocks bounced back in early trading in Asia on Tuesday on the expectation that US-Iran peace talks will resume this week, after earlier meetings in Islamabad broke ⁠down without an agreement. Oil prices had jumped around 6% in Monday trading on doubts over the talks.

Brent crude futures declined 54 cents, or 0.6%, to $94.94 a barrel and US West Texas Intermediate for May fell $1.11, or ​1.2%, to $88.50.

But tensions remained high, with Iran’s foreign ministry on Tuesday condemning the United States for what it called an attack on the Iranian commercial vessel Touska at the weekend, demanding the immediate release of the vessel, its ​crew and their families.

“Iran would use all its capabilities to defend its national interests and security and protect the rights and dignity of its citizens… the United States would bear full responsibility for any further escalation in the region,” it said, according to Iranian state media.

Read more: New Iran deal ‘far better’ than Obama nuclear deal, coming ‘relatively quickly’: Trump

Maritime security sources said on Monday the vessel was likely to have what Washington deems dual-use items that could be used by the military onboard. The US Central Command said Touska’s crew failed to comply with repeated warnings over six hours and the vessel violated the US blockade.

China, the main buyer of Iranian crude, has expressed concern over the “forced interception”.

Iranian Foreign Minister Abbas Araghchi had on Monday said truce violations by Washington were a major obstacle ​to the diplomatic process, while top negotiator Mohammad Bagher Ghalibaf accused Trump on X of increasing pressure through a blockade of Iran’s ports.

He said Trump was deluded in seeking to “turn the negotiating table into a table of submission”, adding Iran ‌rejects negotiations ⁠under threat.

‘They’re going to negotiate,’ Trump says

Thousands of people have been killed by US-Israeli strikes on Iran and in an Israeli invasion of Lebanon conducted in parallel since the war began on February 28. The war triggered a historic shock to global energy supplies and fears that prolonged conflict could push the global economy to the brink of recession.

The US has maintained its blockade of Iranian ports, while Iran lifted and then soon reimposed its own blockade of the Strait of Hormuz, which typically handles roughly one-fifth of the world’s oil and liquefied natural gas supply. Mediator Pakistan has lobbied for Washington to end its blockade.

Trump on the John Fredericks Media Network ​on Monday said Iran would negotiate but reiterated Washington ​would not allow Tehran to develop a nuclear ⁠weapon

“They’re going to negotiate, and hopefully they’ll make a fair deal, and they’ll build their country back up, but they will not have – when they do it – they will not have a nuclear weapon,” Trump said.

The United States has not specified when the two-week ceasefire will end. A Pakistani source involved in the talks said it ​would expire at 8pm Eastern time on Wednesday, or midnight GMT or 3:30am Thursday in Iran.

Pakistan preparing for talks

Pakistan has set the stage for a high-stakes second round of negotiations between the United States and Iran in Islamabad, likely to take place just hours before a Pakistan-brokered ceasefire expires on Wednesday.

Despite lingering uncertainty surrounding ‘Islamabad Round 2’ due to Iran’s reluctance to formally confirm its participation, a US delegation led by Vice President JD Vance is set to travel to the federal capital along with senior officials.

Also read: China says ‘concerned’ over US intercepting Iranian ship in Strait of Hormuz

There was some ambiguity about Vance’s whereabouts, as President Donald Trump told the New York Post that Vance was already on his way to Islamabad, but White House officials said the vice president would depart on Tuesday, with talks expected on Wednesday.

While there was confusion over the exact timing of arrival, there was certainty that the US delegation would be coming. Iran, however, has maintained public suspense, even though developments on the ground in Islamabad suggest a different trajectory.

Even hours after the Iranian Foreign Ministry spokesperson said Tehran had not yet decided whether to join the talks, US military aircraft were seen landing at Nur Khan Airbase, indicating that preparations were moving ahead regardless of the public posture.