The Yemen-based Houthi rebels launched their first attack on a commercial shipping vessel transiting the Red Sea in several months over the weekend, raising concerns that it could be the first in a new wave of such attacks.

A Liberian-flagged cargo ship came under fire Monday in the Red Sea, with two security guards on board reportedly hurt and two others missing in an assault that followed Yemen's Houthi rebels purportedly sinking another vessel in a similar attack.