US-Iran Talks Hit Sudden Setback as Trump Threatens Fresh Strikes, Stock Futures Slide

Key Points

• US-Iran negotiations in Switzerland were thrown into uncertainty after Iranian officials reportedly left the venue in protest over remarks from the US side.
• President Donald Trump escalated pressure on Tehran by warning that the US could strike Iran again if it failed to restrain Hezbollah and reopen the Strait of Hormuz.
• Markets reacted defensively, with oil prices rising and US stock index futures falling as investors reassessed geopolitical risk, energy supply disruption and the outlook for the 60-day negotiation window.

US-Iran Talks Enter Turbulent Phase

US-Iran negotiations in Switzerland took a sudden turn on Sunday after the Iranian delegation reportedly walked out of the venue, accusing the US side of making insulting remarks. The incident marked a sharp deterioration in tone during what was expected to be the first major diplomatic round following the recent memorandum of understanding between Washington and Tehran.

The talks were attended by US Vice President JD Vance, Iranian Foreign Minister Abbas Araghchi and Iranian Parliament Speaker Mohammad Bagher Ghalibaf, with Pakistan and Qatar acting as mediators. The meeting was initially expected to focus on Iran’s nuclear programme, the implementation of the 60-day negotiation framework and steps to stabilise energy flows through the Strait of Hormuz.

Instead, Lebanon and Hezbollah quickly moved to the centre of the discussion. The shift came after the Islamic Revolutionary Guard Corps announced the closure of the Strait of Hormuz in response to Israeli attacks on Hezbollah positions in Lebanon. That decision immediately raised concerns over oil supply, shipping security and the durability of the fragile US-Iran diplomatic track.

Trump Raises Pressure With Fresh Military Threats

The diplomatic setback was amplified by President Trump’s public warnings against Tehran. Trump said the US would strike Iran “very hard again” if Iran did not stop Hezbollah from escalating tensions in Lebanon. He also warned that if the Strait of Hormuz remained closed, the US could respond with severe military force.

The Strait of Hormuz remains one of the world’s most important energy chokepoints, making any disruption highly sensitive for oil markets. Even limited interference with tanker traffic can quickly feed into crude prices, inflation expectations and broader risk sentiment.

Trump also suggested that the US could assume a larger role in securing the Strait of Hormuz if necessary. Such remarks added to investor concerns that the diplomatic process could become entangled with military brinkmanship, maritime security disputes and proxy conflicts across the Middle East.

Iranian officials rejected the threats. Ghalibaf said US pressure would not work on Iran and warned Washington to be careful with its language, adding that Iran’s armed forces were prepared to respond if necessary.

Markets Turn Defensive as Oil Rises and Futures Fall

Financial markets reacted quickly as Monday’s Asian session opened. Brent crude futures rose as much as 1.5%, while WTI crude gained more than 1%, reflecting renewed concern that a prolonged Strait of Hormuz disruption could tighten global energy supply.

US equity futures moved lower across the board. S&P 500 futures fell around 0.72%, while Nasdaq 100 futures dropped more than 1%, showing that investors were reducing exposure to risk assets as geopolitical uncertainty increased.

The market reaction reflects two related concerns. First, higher oil prices could revive inflation pressure at a time when investors are already sensitive to the Federal Reserve’s interest-rate outlook. Second, a wider US-Iran confrontation could weaken confidence in global trade, energy security and corporate earnings visibility.

Technology shares are particularly vulnerable when risk appetite weakens, as higher energy costs and renewed geopolitical stress can weigh on valuation multiples. The Nasdaq’s sharper decline suggests traders were moving away from growth-sensitive assets and into defensive positioning.

Lebanon Issue Complicates Nuclear Negotiation Timeline

The original 60-day negotiation framework was expected to focus mainly on Iran’s nuclear programme, including uranium enrichment, monitoring mechanisms and the disposal or management of enriched material. However, the latest round showed that regional security issues may be just as important to the outcome.

Lebanon has become a major obstacle. Hezbollah remains central to the conflict between Israel and Lebanon, while Iran’s support for the group has long been a major source of tension with the US and Israel. By placing Hezbollah and Lebanon near the top of the agenda, the talks have become broader and more complex than a narrow nuclear negotiation.

That raises the risk that even partial progress on nuclear issues could be delayed by disputes over regional proxies, shipping access and ceasefire implementation. Investors are likely to view this as a negative development because it reduces the chance of a quick diplomatic resolution.

Iran Maintains Its Enrichment Position

Iran has continued to insist that it will not give up its right to enrich uranium. President Masoud Pezeshkian said before the talks that Iran’s enrichment rights were non-negotiable and that the other side would have to accept that position.

According to media reports cited in the original discussion, Iran holds more than 9,000 kilograms of enriched uranium, including hundreds of kilograms of near-weapons-grade material. The memorandum of understanding reportedly calls for both sides to create a mutually agreed mechanism for handling enriched uranium, but the details remain unresolved.

This remains one of the most difficult areas of negotiation. For Washington, limits on enrichment and credible monitoring are essential to any lasting agreement. For Tehran, enrichment is framed as a sovereign right and a matter of national dignity. That gap makes the 60-day timeline challenging, especially if talks are repeatedly disrupted by regional security crises.

Vance Keeps Diplomatic Tone Despite Tensions

Despite the turmoil, Vice President Vance attempted to frame the talks as constructive. He described the negotiations as historic and said meaningful progress had been made over recent hours. His comments appeared designed to keep diplomatic channels open, even as Trump’s remarks increased pressure on Iran.

This contrast between diplomatic engagement and military threats may become a defining feature of the US strategy. Washington appears to be using a dual-track approach: offering negotiations through Vance and allied mediators while using Trump’s public warnings to raise the cost of non-compliance for Tehran.

For markets, however, the mixed messaging adds uncertainty. Investors are likely to remain cautious until there is clearer evidence that the talks can produce a practical agreement on Hormuz access, Lebanon-related tensions and nuclear monitoring.

Outlook: Oil Volatility and Risk-Off Sentiment May Persist

The latest setback does not necessarily mean the diplomatic process has failed, but it does make the path to a final agreement more difficult. The walkout, Trump’s renewed threats and Iran’s firm stance on enrichment all point to a more fragile negotiation environment.

In the near term, oil markets are likely to remain highly sensitive to any headlines involving the Strait of Hormuz. A credible reopening plan could ease crude prices, while further disruptions or military threats could push prices higher and intensify inflation concerns.

Equity markets may also remain under pressure if investors believe geopolitical risk is spreading into energy, shipping and monetary policy expectations. The main risk for global markets is that a regional security dispute turns into a broader confrontation, forcing traders to price in higher energy costs, slower growth and more defensive positioning.

For now, the US-Iran talks remain alive but vulnerable. The next phase will depend on whether mediators can bring both sides back to practical negotiations and whether Washington and Tehran can separate nuclear diplomacy from the expanding regional conflict.