Asia-Pacific Markets Rise Amid US-Iran Vessel Tension

Asia-Pacific stock markets rose on Monday as escalating U.S.-Iran tensions following the seizure of an Iranian vessel kept investors cautious but did not deter buying in key regional indices, with gains seen across Japan, South Korea, Australia, and mainland China despite heightened geopolitical risk.

The Nikkei 225 in Tokyo advanced 0.8% to close at 39,450.30, while the Topix index gained 0.6%. In Seoul, the KOSPI rose 0.5% to 2,680.15, and Australia’s S&P/ASX 200 increased 0.3% to 7,850.20. Mainland China’s Shanghai Composite edged up 0.2% to 3,120.45, and the Hang Seng Index in Hong Kong added 0.4% to 19,850.30.

The U.S. Seizure of the Iranian-flagged vessel Saviz in the Gulf of Oman on April 19, 2026, prompted sharp reactions from Tehran, which condemned the action as “piracy” and warned of potential retaliation. The ship, reportedly used for maritime surveillance, was intercepted by U.S. Forces operating under the Combined Maritime Forces (CMF) task force based in Bahrain.

Iran’s Foreign Ministry summoned the Swiss ambassador, who represents U.S. Interests in Iran, to protest the move. Iranian state media reported that the Islamic Revolutionary Guard Corps (IRGC) navy had been placed on heightened alert in the Strait of Hormuz, a critical chokepoint for global oil shipments.