Yemen’s Houthis announced Monday the immediate launch of a “maritime embargo” against Saudi Arabia.

The Houthis cited “the targeting of Sana’a International Airport” and Saudi Arabia’s “siege…for nearly twelve years.” It was not immediately clear how the Houthis planned to enforce its embargo or how narrowly Saudi assets would be targeted.

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Saudi Arabia currently exports energy westward to the Red Sea ports of Yanbu and Jeddah, which the Houthis may seek to disrupt. NBC News reports that “the full closure of the Bab el-Mandeb strait would reduce global oil supply by 7 percent as it would leave most of Saudi oil exports unable to leave the region.”

That Saudi pipeline to the Red Sea port of Yanbu, which exports up to 5 million barrels of barrels of oil per day, has become an alternative route to the Strait of Hormuz and has been credited with partially offsetting the hit to global oil supply caused by Hormuz’s closure.