Iran is celebrating the Houthis' rapid advance toward Bab el-Mandeb, but appears reluctant to act on the win.

The renewed fighting in Yemen is testing one of Iran's most valuable regional partnerships just as Tehran scrambles to preserve its remaining leverage.

Riyadh is balancing pressure on the Houthis with efforts to keep Iran from widening the conflict, as attacks threaten Saudi energy exports through the Red Sea.

Houthi control of a Red Sea port brings Tehran closer to claiming another critical waterway.