President Donald Trump said the military action was a response to Iran's attempt to lay mines in the Strait of Hormuz and to Iran's earlier strikes on a US military base in Jordan, and he warned of further strikes if Iran retaliates. ^[1] US Central Command said that US forces struck targets belonging to Iran's Revolutionary Guard. ^[2] Brent crude for December delivery rose 4.1% to $95.4 per barrel and WTI crude for October rose 0.4% to $90.6 per barrel on 2026-09-01, as US strikes on Iran heightened Middle East tensions. ^[3] Major global stock indices fell on 2026-09-01, with the Dow Jones down 0.79%, S&P 500 down 0.71%, Nasdaq down 1.03%, FTSE 100 down 0.32%, CAC 40 down 0.39%, DAX 40 down 1.10%, FTSE MIB 30 down 1.33%, Kospi down 3.4%, Nikkei 225 down 3%, Hang Seng down 1%, Shanghai Composite down 1%, and BIST 100 down 0.73% to 14,229.01. ^[4] The US 10-year Treasury yield rose to 4.82% on 2026-09-01, the highest since November 2023, while the 2-year yield reached 4.42%, the highest since January 2025. ^[5] US President Donald Trump announced on 2026-09-01 that the US conducted new strikes against Iran, warning that Iran would face a larger attack if it retaliated. ^[6] Korea's KOSPI index fell 158.31 points, or 2.32%, to close at 6677.49 on Tuesday morning. ^[7] The KOSPI index opened down 210.33 points, or 3.08%, at 6625.47 due to rising oil prices and US-Iran military tensions. ^[8] The market declines were driven by US strikes on Iran and fears that higher energy costs would force the Federal Reserve to tighten monetary policy later in the month. ^[9] Retail investors purchased 642.3 billion won in the KOSPI market, absorbing the selling pressure from foreign and institutional investors. ^[10] Samsung Electronics shares fell 2.87% to 253,500 won, and SK Hynix shares fell 2.66% to 1,648,000 won. ^[11]