Yemen’s Houthi forces have attacked several commercial ships crossing through the Bab el-Mandeb strait in recent days, creating a new front in the battle between Israel and Hamas and complicating efforts by the U.S. and its allies to secure the critical shipping lane.

Houthi rebels claimed responsibility on Tuesday for a strike on the Norwegian tanker Strinda a day earlier off Yemen’s coast, as the Iranian ally escalates attacks to disrupt the flow of cargoes in response to fighting in Gaza. The elevated risk of moving cargoes through the region has resulted in higher costs for shippers and also prompted some countries to rethink security measures to allow safe passage.