U.S. Vice President JD Vance was reported to be traveling to Pakistan for the talks, with Axios citing three American sources who said he would depart the United States by Tuesday morning, according to BBC Persian. However, Iran had still not confirmed its participation. Iranian state television flatly denied that any delegation — either principal or preliminary — had arrived in Islamabad, calling media reports of a scheduled Iranian arrival "baseless," Al Jazeera reported. A Pakistani source cited by Reuters told Iran International that the second round of talks was nonetheless scheduled for Wednesday.
The diplomatic uncertainty came against a backdrop of sharp rhetoric from both capitals. President Donald Trump, on the 14th day of the ceasefire, expressed hope that Tehran would reach "a fair deal," but warned that Iran's refusal to negotiate would expose it to "unprecedented problems," according to Al Jazeera. Trump also posted on Truth Social that "Operation Midnight Hammer" — a 12-day U.S. military campaign that struck Iran's Fordow, Natanz, and Isfahan nuclear facilities — had achieved "complete and total destruction," and that recovering Iran's enriched uranium stockpile would be "a long and difficult process," BBC Persian reported.
Tehran pushed back on every front. Mohammad Baqer Qalibaf, speaker of Iran's parliament and head of its negotiating delegation, declared that Iran "will not accept negotiations under the shadow of threats," and said his team had spent the past two weeks "preparing to reveal new cards on the battlefield," according to BBC Persian. The commander of Iran's Khatam al-Anbiya Central Headquarters warned that armed forces would respond to "any breach of commitment" with a "superior hand," calling Trump "a liar and a delusional person," BBC Persian reported. Iranian state television added that Tehran's continued participation in any talks was conditional on Washington changing "its behavior and positions."
Tensions extended to the seas. The U.S. Navy seized the Iranian-flagged commercial vessel Tosca in the Gulf of Oman on April 19, with U.S. Central Command releasing footage of the interception. Iran's Foreign Ministry condemned the seizure as "illegal" and "terrorist," demanding the "immediate release" of the ship and its crew, and warning of "very dangerous consequences," according to BBC Persian. Trump said the United States would not end its naval blockade of Iranian ports until a deal was reached, while the Iranian navy reported that an oil tanker had returned to Iranian territorial waters overnight with naval support, defying what Tehran described as a U.S.-imposed blockade, Al Jazeera reported.
The global energy market watched closely. The International Energy Agency's director Fatih Birol described the situation as "the biggest crisis in history," noting that one-fifth of the world's oil and natural gas passes through the Strait of Hormuz, according to BBC Persian. Oil prices fell in Asian markets on Tuesday as investors awaited clarity on whether the Islamabad round would proceed, with Brent crude dropping 1.6 percent to $93.97 a barrel, Iran International reported. Bloomberg reported that the International Maritime Organization was drawing up evacuation plans for hundreds of vessels stranded in the Strait of Hormuz, according to Al Jazeera.
International pressure mounted for a diplomatic solution. Germany's Foreign Minister urged Iran to "come quickly to Islamabad and negotiate constructively," saying Tehran should "seize this opportunity for the sake of its own people," according to Al Jazeera and BBC Persian. Spain, Slovenia, and Ireland asked the European Union to discuss suspending its partnership with Israel, with Spain's foreign minister describing the regional situation as "the biggest crisis in the Middle East since the Gulf War," Sky News Arabia reported. The EU's foreign policy chief called the ceasefire "very fragile" and expressed hope for its extension, while France urged all sides to prevent a collapse of the Lebanon ceasefire, Al Jazeera reported.
Inside Iran, the war's domestic toll was mounting. Internet access had been severed for 53 consecutive days since the outbreak of hostilities, with daily economic losses from the blackout estimated at $30–40 million, according to BBC Persian. Human rights monitors warned that Iranian courts were accelerating executions, using the death penalty "as a tool to suppress political dissent in wartime conditions," BBC Persian reported.
BBC security correspondent Frank Gardner cautioned that any expectation of a rapid breakthrough was misplaced, noting that the original JCPOA nuclear deal required 18 months of intensive negotiations among highly experienced diplomats — "such a complex agreement is not something that can be achieved in days," according to BBC Persian. With the ceasefire set to expire Wednesday and both sides publicly holding firm, the window for diplomacy in Islamabad remained open — but narrow.