There are two more tankers on fire in the Persian Gulf, and it’s starting to look like the Persian Gulf has a small tanker war in the making. Secretary of State Mike Pompeo says Iran blew up two ships on Thursday, four last month, and claims the U.S. has the evidence to prove it—although he hasn’t shown us any proof yet. So who would want to target Norwegian and Japanese tankers? How would Iran carry out a covert tanker sabotage operation? And are Iran’s alleged attacks on its neighbors going to end up sucking the U.S. into another conflict?

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Maximum pressure: The answer to why Iran might have targeted tankers from Japan and Norway—two countries it’s hardly at war with—might be found in their cargo. In May, the Trump administration announced a new wave of sanctions that targeted Iran’s petrochemical industry. During a visit with Japanese Prime Minister Shinzo Abe on Thursday, Iran’s supreme leader, Ayatollah Ali Khamenei, called out those sanctions in particular, which makes the two ships targeted in Thursday’s explosion all the more interesting.