DUBAI, United Arab Emirates—Yemen’s Houthi rebels seized a ship in the Red Sea, armed drones targeted Baghdad’s international airport, and hackers hit a major Israeli newspaper Monday—a string of assaults that showed the reach of Iran-allied militias on the second anniversary of America’s killing of a top Iranian general. All three coincided with a massive memorial in Tehran for Qassem Soleimani, the terrorist leader killed by a U.S. drone strike in 2020 in Iraq. The taking of the Emirati ship Rwabee marks the latest assault in the Red Sea, a crucial route for international trade and energy shipments. The Iranian-backed Houthis acknowledged the seizure off the coast of Hodeida, a long-contested prize of the grinding war in Yemen between the rebels and a Saudi-led coalition that includes the United Arab Emirates. First word of the Rwabee’s seizure came from the British military’s United Kingdom Maritime Trade Operations, which only said …