The U.S. dollar strengthened across Asian markets on Friday, climbing to a one-year high as growing doubts about the implementation of the tentative U.S.-Iran peace agreement pushed investors back toward the world’s dominant reserve currency, while the Japanese yen hovered near levels that could trigger another round of government intervention.
The development shows that while traders initially welcomed the breakthrough between Washington and Tehran, the path from a ceasefire framework to a durable peace agreement remains highly uncertain. That uncertainty is limiting appetite for risk-sensitive currencies and helping sustain demand for the dollar despite expectations that lower oil prices could eventually ease inflation pressures.
The dollar index, which measures the greenback against six major currencies, rose 0.3% to 101.07, its highest level in a year. The advance came after fresh doubts emerged over negotiations intended to formalize the agreement reached earlier this week between the United States and Iran.
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A key source of concern was the abrupt postponement of talks that were expected to take place in Switzerland. U.S. Vice President JD Vance abandoned plans to travel to the country for negotiations with Iranian officials, raising questions about how quickly the agreement can be translated into concrete actions.
Swiss authorities confirmed that negotiations scheduled at the mountain resort of Burgenstock would not take place on Friday. The cancellation came even as Iranian officials had previously indicated readiness to begin technical discussions following the 14-point accord that extended the ceasefire by at least 60 days.
The White House attempted to downplay concerns, saying the logistics surrounding the negotiations had always been complex and unpredictable. However, financial markets interpreted the delay as a reminder that major obstacles remain.
Iran has signaled that it wants evidence that Washington is implementing the interim agreement before committing fully to the next phase of negotiations. Iranian media reports suggested there was still no confirmation that Tehran’s delegation would travel to Switzerland. Adding to the uncertainty, Iran’s foreign ministry cast doubt on a proposed signing ceremony that U.S. officials had discussed, arguing that such an event was unnecessary because both countries’ presidents had already signed the framework agreement.
These developments have bolstered concerns that the diplomatic breakthrough remains fragile. For currency markets, the issue extends well beyond the Middle East.
Investors had initially viewed the agreement as a catalyst that could reopen the Strait of Hormuz, restore stability to energy markets, and reduce inflationary pressures that have complicated central bank decision-making worldwide. A durable agreement could potentially support global growth, improve trade flows, and reduce demand for safe-haven assets such as the U.S. dollar.
But the latest setbacks suggest the process may be lengthy and vulnerable to political disagreements, implementation disputes, and regional tensions.
As a result, many investors are reluctant to abandon defensive positions.
The renewed dollar strength also reflects changing expectations surrounding U.S. monetary policy. Markets are increasingly reassessing the likelihood that the Federal Reserve could maintain a tougher stance on inflation following comments from Fed Chairman Kevin Warsh and several policymakers who have emphasized the need to restore price stability.
Fed funds futures now imply a sharply higher probability of a rate increase in the coming months compared with expectations only a week ago. Higher U.S. interest rates typically strengthen the dollar by attracting foreign capital into Treasury securities and other dollar-denominated assets.
The Japanese Yen Remains Under Intense Pressure
The currency traded around 161.46 per dollar, close to levels widely viewed as intervention territory by market participants. The weakness has persisted despite substantial efforts by Japanese authorities to stabilize the currency, including direct intervention and the Bank of Japan’s recent interest-rate increase to its highest level in more than three decades.
Yet the fundamental drivers remain largely unchanged.
Japan continues to face a significant interest-rate disadvantage relative to the United States, encouraging investors to move capital abroad in search of higher returns. Concerns over Japanese fiscal policy and government spending plans have also undermined confidence in the yen.
Analysts believe Tokyo may be forced to intervene again if the currency approaches the 162 level.
“Our view is that Japan’s Ministry of Finance will likely defend the 161.95 level the first couple of times it’s tested, deploying similar firepower to what we saw in ?April and May — around 11.7 trillion yen,” said Tony Sycamore, market analyst at IG in Sydney.
“That would mean they would have used ?roughly 11–12% of their ?total reserves in a relatively short period, with little noticeable impact,” he added. “At that stage, they would need to become far more selective with future interventions to preserve flexibility and credibility, keeping plenty of ammunition in reserve.”
Minutes from the central bank’s meeting in April released on Friday ?morning, and comments soon after from BOJ ?Deputy Governor Ryozo Himino also cautioned there ?could be more rate hikes tied to the inflationary effects of the Iran war.
The challenge for Japanese authorities is that previous interventions have delivered only temporary relief. Earlier operations consumed trillions of yen from foreign-exchange reserves without fundamentally reversing the currency’s direction. That raises questions about how much firepower policymakers are willing to deploy if speculative pressure intensifies.
Elsewhere, most major currencies weakened against the dollar. The euro slipped to $1.1419, sterling fell to $1.3174, while the Australian and New Zealand dollars also retreated.
The broader message from currency markets is that investors remain unconvinced that the geopolitical risks that drove volatility across global markets earlier this year have fully disappeared.
Even though oil prices have fallen and hopes for peace have improved sentiment compared with the height of the conflict, the suspension of key negotiations demonstrates that substantial hurdles remain. Questions surrounding sanctions relief, verification mechanisms, implementation timelines, nuclear restrictions, and regional security arrangements are still unresolved.
Until those issues are addressed and a comprehensive agreement is formally implemented, economists have warned that global currencies are likely to remain vulnerable to sudden swings in sentiment.
For now, the dollar continues to benefit from that uncertainty. While markets would normally expect easing geopolitical tensions and falling oil prices to weaken the greenback, the unresolved nature of the U.S.-Iran negotiations, combined with a more hawkish Federal Reserve, is creating a powerful counterweight.
That leaves currency markets caught between optimism over a potential peace dividend and caution over whether the agreement can survive the difficult negotiations that still lie ahead.