War planning for Iran is now the most pressing scenario, or what the Pentagon calls a contingency.

U.S. Central Command believes it can destroy or significantly degrade Iran’s conventional armed forces in about three weeks using air and sea strikes, according to a defense source familiar with the discussions.

Such strikes are an option in a response to Tehran’s striking U.S. and international ships in the Persian Gulf and attempting to close the strategic Strait of Hormuz, through which about one-fifth of the world’s oil is transported.