Israel has targeted at least a dozen vessels bound for Syria and mostly carrying Iranian oil out of concern that petroleum profits are funding extremism in the Middle East, U.S. and regional officials say, in a new front in the conflict between Israel and Iran. Since late 2019, Israel has used weaponry including water mines to strike Iranian vessels or those carrying Iranian cargo as they navigate toward Syria in the Red Sea and in other areas of the region. Iran has continued its oil trade with Syria, shipping millions of barrels and contravening U.S. sanctions against Iran and international sanctions against Syria.

Some of the naval attacks also have targeted Iranian efforts to move other cargo including weaponry through the region, according to U.S. officials. The attacks on the tankers carrying Iranian oil haven’t been previously disclosed. Iranian officials have reported some of the attacks earlier and have said they suspect Israeli involvement. Israel hasn’t commented previously on such incidents and Israeli Prime Minister Benjamin Netanyahu’s office referred questions to the Israeli military, which declined to comment on any Israeli role in the attacks on the Iranian ships. Iranian officials at the country’s United Nations mission didn’t respond to a request for comment.

Damascus has said disruptions of Iranian oil imports are causing shortages for Syrians. Syria and Iran have denied funding terrorism and say their alliance is aimed at countering such crime.

The disclosure of the Israeli campaign at sea marks a new dimension in its campaign to counter Iran’s military and economic entrenchment and its support of allied groups in the region. Since 2018, Israel has conducted hundreds of airstrikes, mostly in Syria, to rout Iranian-backed groups, weapons and influence across the region.