Israel has been mounting covert attacks on Iranian ships carrying oil to Syria, according to a report in the Wall Street Journal.
It said that at least dozen ships have been struck, mostly by mines, since late 2019, with two forced to return to Iran.
The operations led to an oil spill in the Red Sea in October 2019, the paper reported, quoting US sources.
Iran is currently investigating an explosion on board a cargo ship, the Shahr e Kord, off the Syrian port of Latakia on Wednesday night; no one on board was reported hurt.
