Today's D Brief: Anti-Houthi strikes get a name; Autonomous weapons advance; B-21 production greenlit; Assessing a Taiwan invasion; And a bit more.

The U.S. and British militaries conducted more airstrikes in Yemen Monday at midnight local time. Like the January 11 strikes, these featured a multinational ensemble that included Australia, Bahrain, Canada, and the Netherlands helping in an unspecified manner. But only the Brits and Americans carried out the actual attacks, using “air, surface, and sub-surface platforms” to launch Tomahawk Land Attack Missiles and other precision-guided munitions, a U.S. military official said.

Eight different strikes hit missile systems and launchers, air defense systems, radars, and “deeply buried weapons storage facilities,” according to officials at Central Command. “We observed good impacts and effects at all eight locations, assessing that we did in fact destroy missiles, unmanned aerial systems, and weapons storage areas,” a military official told reporters Monday. 

As for the “deeply buried” weapons storage site, “this would be the first time we struck a storage facility of this type in Yemen,” the official said. That target was chosen because it “was assessed to have more advanced conventional weaponry” than anything the U.S. or British hit on January 11. 

Fine print: “These strikes, while necessary, do not indicate a shift in our approach to the region,” a U.S. defense official said. “This action, grounded in Article 51 of the United Nations Charter, reflects our inherent right to self-defense,” they said, and added, “We stand ready to take further actions to neutralize threats or respond to attacks, ensuring the stability and security of the Red Sea region and international trade routes.”

By the way, the U.S. military’s newest airstrike campaign in Yemen now has a name: Operation Poseidon Archer, defense officials told CNN on Monday. This means there are now two distinct but geographically overlapping U.S.-led multinational naval operations taking place in the vicinity of the Red Sea—the more defense-oriented, 22-nation Operation Prosperity Guardian to protect commercial shipping; and this more recent Poseidon Archer mission, which is intended to degrade the Houthis’ missile-launching capabilities. The idea is “to chip away at the Houthis’ ability to menace merchant ships but not hit so hard as to kill Houthi fighters and commanders, and potentially unleash an even wider war,” Eric Schmitt of the New York Times writes. 

View a map of the Red Sea and Gulf of Aden illustrating approximate locations of recent Houthi attacks on ships traveling nearby, via Damien Symon, who used data compiled by our recent podcast guest, Fabian Hinz of the International Institute for Strategic Studies. 

Apropos of nothing, we recently learned that “The US is producing more oil than any country in history, some 13 million barrels of it per day, and all those barrels are coming at OPEC’s expense,” according to Quartz, reporting Thursday.

From the region: Two British Royal Navy warships slowly crashed into each other last week in Bahrain. Video of the collision, which was quite loud and crunchy, can be viewed here. Officials attributed the collision to “faulty wiring,” which sent minehunter HMS Chiddingfold backwards into the HMS Bangor, ripping a hole in the latter just above the waterline, according to the Guardian

Also: The British navy says it has successfully tested a new laser weapon that can shoot down drones. The Brits call it DragonFire, and it requires about 10 seconds of contact with the target for it to work. 

Caveat: “It cannot be fitted to existing Royal Navy ships,” the defense ministry said, “but it could be installed on those currently under construction such as Type 26 or 31 frigates.” The British army is also looking into mounting it on tanks and armor in the coming months and years. More, here.

Welcome to this Tuesday edition of The D Brief, brought to you by Ben Watson with Bradley Peniston and Jennifer Hlad. Share your newsletter tips, reading recommendations, or feedback for the year ahead here. And if you’re not already subscribed, you can do that here. On this day in 1960, Swiss oceanographer Jacques Piccard and U.S. Navy lieutenant Don Walsh traveled deeper below the ocean's surface than anyone before or since when they descended in the Trieste to a depth of 35,814 ft in the Mariana Trench's Challenger Deep.

China would struggle to invade Taiwan, writes David Sacks of the Council on Foreign Relations, which offers a vividly illustrated argument for why this is so: video of the wind-whipped waters of the Taiwan Strait, maps showing the paucity of invadable ports and beaches, and so forth. Find that here.

Trump declines to declare his support for Taiwan against China, saying the self-governing island “took our business away” by building the world’s best chip fabs. He spoke recently to Fox’s Maria Bartiromo.

New: B-21 production is a go. Northrop Grumman received the Pentagon’s approval to start low-rate production of the new stealth bomber, William LaPlante, defense undersecretary for acquisition, confirmed in a Monday evening statement. Northrop has already built six test aircraft, but the approval for production had to wait until after the plan made its first flight in November, D1’s Audrey Decker reports. The company will hold its earnings call for the final quarter of 2023 on Thursday.

Developing: Recent Pentagon breakthroughs in experimental aerial and naval craft are paving the way for low-cost attack drones and new tactics that feature AI in key roles, Defense One’s Patrick Tucker reported Monday. 

The Navy, for example, brought swarms of air and sea drones to the annual Unitas exercise, where they collected and shared reconnaissance data that helped the multinational fleet detect, identify, and take out enemy craft more quickly.

And the Air Force is “testing things like the XQ-58 high-performance drone that is uncrewed and has AI-enabled functionality,” Col. Tucker Hamilton, Operations Commander of the Air Force’s 96th Test Wing, said last Tuesday. Additionally, “We actually, for the first time in the history of aviation, had an AI agent and AI algorithm fly a high-performance drone” last July at Eglin Air Base, Florida, he said. Read on, here.