Today's D Brief: Terrorism in Moscow; Iraqi PM gets WH invite; Houthis attack Chinese tanker; Shakeup at Boeing; And a bit more.

Terrorists attacked a concert hall in Moscow Friday, killing more than 130 people in an attack Russian leader Vladimir Putin tried to link with Ukraine, alleging the attackers headed toward Ukraine after the violence.

The ISIS affiliate in Afghanistan, ISIS-K, claimed responsibility for the attack. The same group tried to attack France, which increased a nationwide security alert to its highest level this weekend, Reuters reports. 

Russian authorities arrested four men from Tajikistan allegedly involved in the attack. Their names and ages are Dalerdzhon Mirzoyev, 32; Saidakrami Rachabalizoda, 30; Shamsidin Fariduni, 25; and Mukhammadsobir Faizov, 19, according to investigators. They all appeared in court Sunday on terrorism charges. Each seemed to show “signs of severe beatings,” and “One appeared to be barely conscious during the hearing,” according to the Associated Press

White House officials condemned the attack, and noted “ISIS is a common terrorist enemy that must be defeated everywhere,” according to a statement Saturday from Press Secretary Karine Jean-Pierre. CNN has the latest developments in this story in a live blog, here.

Welcome to this Monday edition of The D Brief, brought to you by Ben Watson with Lauren C. Williams. 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 1948, the world's first tornado forecast was issued while conditions for what we'd describe today as an F3 storm began developing in the vicinity of Oklahoma's Tinker Air Force Base.

The White House has invited Iraqi Prime Minister Mohammed Shia’a Al-Sudani to Washington for discussions with President Biden on April 15, which is almost two years since Sudani took the job amidst a crisis in Iraqi politics. Such a meeting had been considered a possibility for some time, according to Middle East scholars like Mike Knights and Charles Lister

For many months, a top White House consideration was exactly when might be among the best times to signal Biden’s approval at the direction of Iraq with Sudani at the helm—while also trying to avoid bold military action that might spur a binding eviction by Iraqi parliamentarians, many of whom have strong sympathies with Iran.  

Remember, U.S. forces in the region ostensibly fighting ISIS have been attacked by Iran-backed militias more than 170 times over the past six months, or since Hamas militants attacked Israel on October 7. (View a full accounting of those attacks via the Washington Institute, here.) The most serious of those attacks in late January killed three U.S. soldiers and wounded more than 40 others at a remote base in Jordan known as Tower 22.

But those reported attacks on U.S. troops have receded almost entirely since mid-February, shortly after Biden authorized a retaliation campaign of airstrikes in Iraq and Syria following the three soldiers’ deaths. A top Iranian commander also visited Baghdad to quiet those militias for a while after the U.S. strikes, according to Reuters

According to Mike Knights of the Washington Institute, writing in early February: “Sudani needs to earn his visit to the White House by providing ‘that he is more than the general manager for a cabal of terrorists running today’s Iraq.’” He also has five recommendations that he would ask of Sudani if he were calling the shots. Read over those, here

According to the White House’s plans for April, the two leaders “will consult on a range of issues during the visit, including our shared commitment to the lasting defeat of ISIS and evolution of the military mission nearly ten years after forming” the counter-ISIS coalition. 

The latest official U.S. position regarding its ongoing war against ISIS: “It's going to take some time” still before the U.S.-led coalition feels the terrorist group is harmless enough to voluntarily withdraw from bases in Iraq and Syria. That was the feedback from U.S. Ambassador to Iraq Alina Romanowski, speaking to Reuters over the weekend. “In the past we have left quickly only to come back, or only to need to continue, so this time I would argue we need to do this in an orderly fashion,” she added. 

Related reading: 

The Iran-backed Houthis in Yemen attacked a Chinese-owned oil tanker in the Red Sea on Saturday, U.S. defense officials at Central Command announced Sunday. 

Involved: ​​M/V Huang Pu, which is a Panamanian-flagged, Chinese-owned, Chinese-operated tanker ship. 

After the Houthis missed the ship using four anti-ship ballistic missiles before sunrise, a fifth missile is believed to have struck in the afternoon and caused “minimal damage,” igniting a fire on board that was extinguished within 30 minutes, according to CENTCOM. “No casualties were reported, and the vessel resumed its course,” the U.S. defense officials said. 

The U.S. Navy fired at about a half dozen Houthi aerial drones flying over the Red Sea just after sunrise Saturday. “Five crashed into the Red Sea, and one flew inland into Houthi-controlled areas of Yemen,” CENTCOM said in a statement. U.S. forces destroyed four other Houthi flying drones inside Yemen throughout the day on Friday. 

The U.S. also attacked “three Houthi underground storage facilities in Iranian-backed Houthi terrorist-controlled areas of Yemen” on Friday, CENTCOM announced separately over the weekend. “These strikes targeted capabilities used by the Houthis to threaten and attack naval ships and merchant vessels in the region,” CENTCOM officials said. 

Update: An American sailor fell overboard while working on the USS Mason Wednesday in the Red Sea. He was 34-year-old Florida native Navy Petty Officer Oriola Michael Aregbesola. He’d been assigned to the “Swamp Foxes” of Helicopter Maritime Strike Squadron 74, according to the Navy. More, here

Additional reading: 

Lawmakers on Friday passed a $1.2 trillion, six-bill budget package with $825 billion for the Defense Department, or roughly $30 billion more than what Congress enacted in 2023, Defense One’s Audrey Decker and Patrick Tucker report. That means about $92 million for the Pacific Deterrence Initiative; $108 million for Taiwan support (more than requested); and about $300 million for the Ukraine Security Assistance Initiative. 

The bill also gave the Navy $33.5 billion for new battleships and submarines and fully funded the Pentagon’s request for new aircrafts—86 F-35 fighter jets, 15 KC-46 tankers, and 24 F-15EXs.  

The U.S. Army put drones front and center in newly obtained budget docs. Service leaders said they want another $35 million in fiscal 2025—$10 million for small drone-making companies and $25 million to buy commercial drones for infantry combat brigade teams, according to unfunded priority lists given to Congress. 

Army Chief of Staff Gen. Randy George has emphasized drone acquisition after the service branch canceled the Future Attack Reconnaissance Aircraft program and is pivoting from existing drone platforms. “We're going to see robotics inside the formation, on the ground and in the air,” he told Defense One’s Sam Skove.

The Army also wants more electronic warfare tools on the front lines. Once 2024 funds are dispersed, the plan is to start doling out EW backpacks to bases to prepare soldiers for defending against adversaries and help commanders understand how visible they are on the digital battlefield, Maj. Gen. Paul Stanton, head of the Army’s Cyber Center of Excellence, told Defense One’s Lauren C. Williams. 

“Until you've been jammed, you don't know that you're being jammed. And so how do our maneuver formations react to the fact that they're fighting in a contested environment?” Stanton said. “We have to let commanders know what they look like in their own backyard.” 

And lastly: Three top Boeing executives, including CEO Dave Calhoun, will step down amid several quality control incidents, the Washington Post reported Monday. Calhoun will leave at the end of 2024 while the CEO for commercial airplanes, Stan Deal, will retire effective Monday. Board chair Larry Kellner said he will not seek re-election in an upcoming shareholder meeting. Story, here.