The United States on Sunday carried out a second night of airstrikes against Iranian targets as their dispute over transit rights in the Strait of Hormuz threatened to escalate beyond the region. U.S. Navy file photo by Mass Communication Specialist Seaman Zoe Simpson

July 12 (UPI) -- The U.S. military said Sunday it is carrying out a second consecutive night of airstrikes against Iranian targets as world leaders raised fears that a fragile cease-fire would collapse and the conflict could widen beyond the region.

The U.S. Central Command said in a statement its forces "began launching more strikes against Iran to continue degrading their ability to attack civilian mariners and commercial ships freely transiting the Strait of Hormuz.

"The Commander in Chief has directed the strikes to hold Iranian forces accountable."

The new wave of strikes came hours after the U.S. military refuted Iran's claims it had closed the vital waterway in response to what it characterized as violations of the 25-day-old U.S.-Iran memorandum of understanding which established the shaky cease-fire.