Yemen’s rebel Houthi movement has announced a “maritime blockade” on Israel’s Haifa port, warning commercial shipping companies to steer clear or risk becoming a target, according to Breakbulk News.

In a televised statement reported by Reuters May 19, the group’s military spokesperson, Yahya Saree, said Haifa port had been officially added to the group’s list of maritime targets. He warned all shipping companies operating vessels bound for, or currently docked at, Haifa to change course immediately.

“All companies with ships present in or heading to this port are hereby notified that, as of the time of this announcement, the aforementioned port has been included in the list of targets,” Saree said.

So far, despite ongoing attacks, most Houthi-fired missiles aimed at Israel have been intercepted by Israel’s Iron Dome and other defense systems. But, for many months, the Houthis’ ability to project force across hundreds of miles has kept shippers on edge, and forced a significant rerouting of global trade.

Earlier this year, the Houthis agreed to halt attacks on U.S.-flagged vessels after Washington ramped up retaliatory strikes. But vessels flagged under U.S. allies or shipping to Israeli ports have remained vulnerable.