“A whole civilization will die tonight,” Trump said on social media, amplifying an earlier vow to level bridges, power plants and other civilian infrastructure if the country does not reopen the Strait of Hormuz to oil-tanker traffic.

Stocks had risen Monday on hopes for a ceasefire, but the Dow Jones Industrial Average fell 0.7% early Tuesday to 46,368.33.

About 10 minutes into trading, the broad-based S&P 500 dropped 0.5% to 6,576.59, while the tech-rich Nasdaq Composite Index shed 0.6% to 21,859.32.

Markets view Trump’s extreme rhetoric as a negotiating tactic, said David Waddell, chief investment strategist at Waddell & Associates.

“The markets are taking it in stride because they’ve learnt not to over-index Trump’s threats, recognising it’s probably more negotiation than reality,” Waddell said.