Nigeria, March 10 -- "If Iran does anything that stops the flow of oil within the Strait of Hormuz, they will be hit by the United States of America twenty times harder than they have been hit thus far," Mr. Trump wrote on social media. He added that the United States could target sites in Iran that would make it "virtually impossible" for the country to rebuild, while warning that "death, fire, and fury will reign upon them." He also said he hoped such a scenario would not occur.

The warning comes as tensions in the region enter their 11th day, following airstrikes by U.S. and Israeli forces against Iranian targets. According to United States Central Command, more than 5,000 Iranian targets have been hit since 28 February, and about 50...