DUBAI, United Arab Emirates — The U.S. blamed Iran for suspected attacks on two oil tankers Thursday near the Strait of Hormuz, denouncing what it called a campaign of “escalating tensions” in a region crucial to global energy supplies.

The U.S. Navy rushed to assist the stricken vessels in the Gulf of Oman off the coast of Iran, including one that was set ablaze. The ships’ operators offered no immediate explanation on who or what caused the damage against the Norwegian-owned MT Front Altair and the Japanese-owned Kokuka Courageous. Each was loaded with petroleum products, and the Front Altair burned for hours, sending up a column of thick, black smoke.

U.S. Secretary of State Mike Pompeo said the assessment of Iran’s involvement was based on intelligence, as well as the expertise needed for the operation. It was also based on recent incidents in the region the U.S. also blamed on Iran, including the use of mines designed to be attached magnetically to a ship’s hull to attack four oil tankers.