Oil prices fall as U.S. pledges economic pressure on Iran; Asian markets slip

Oil prices fell on Monday as investors awaited details of a U.S. plan to isolate the Iranian economy. President Donald Trump described the plan as the "most crushing" financial operation ever against Tehran.

Asian stocks were mostly lower in early trading. South Korea's Kospi fell 1.4% after Samsung Electronics said it spent $80 billion to buy back its own shares following weeks of turbulent trading. Samsung's shares, along with those of rival SK Hynix, had peaked in June on optimism about an artificial intelligence boom but have since declined amid investor jitters and a broader technology sell-off.

Investors were also looking ahead to an earnings report from Nvidia, the world's most valuable company and a bellwether for the tech sector, in what was described as an important week for AI-related markets.