Oil, stock markets fluctuate after US says to blockade Strait of Hormuz

Global markets were once again on edge after US President Donald Trump posted on social media Monday that the US would begin blocking vessels entering and leaving Iranian ports starting 10 a.m. Eastern Time on April 13.

Both WTI and Brent crude oil futures surged on Monday by about 8% at the open, with both prices climbing back above the $100 per barrel mark, Market Watch data showed.

US S&P 500 stock futures fell about 0.5%. 

By market close, Japan's Nikkei 225 index dropped by 0.74% while the KOSPI Composite index fell by 0.86%.

The US dollar strengthened as investors rushed to safe-haven assets.

The latest US action has introduced a second layer of control over navigation in the Strait of Hormuz, and the area is now in a "controlled and unstable" state with the risk of direct conflict between state actors increasing, UK-based maritime analysis company Windward said in a report.

US Vice President JD Vance on Sunday said the US and Iran failed to reach any agreement. Vance told a press conference in Islamabad, Pakistan, that the US team will return to the United States "without an agreement" due to significant differences on several key issues.

Iran's chief negotiator Mohammad Bagher Ghalibaf told several Iranian news agencies on Sunday that Iran will not be pressured by threats after US President Donald Trump announced a blockade of the Strait of Hormuz.