Today's D Brief: US bulks up Gulf forces; SecDef to visit IndoPac; Afghanistan’s lessons for Ukraine war; Tuberville block awaits Army, Air Force chief noms; And a bit more.

The Pentagon is sending more than 2,000 Marines and several U.S. Navy ships to the Middle East in response to increasingly aggressive Iranian actions in the region, U.S. Central Command announced Thursday. An unnamed Amphibious Ready Group/Marine Expeditionary Unit will join a guided missile destroyer and F-35 and F-16 fighter jets dispatched on Monday to the waters near Oman. 

The buildup comes two weeks after the U.S. Navy said one of its guided-missile destroyers stopped the Iranian navy from seizing two commercial tanker ships in the Gulf of Oman and Strait of Hormuz, including one it shot at during the takeover attempt. And that was not an isolated incident; Iran has “attacked, seized, or attempted seizure of nearly 20 internationally flagged merchant vessels in the CENTCOM area of operations” in the past two years, U.S. military officials said Thursday.

“These additional forces provide unique capabilities, which alongside our partner nations in the region, further safeguard the free flow of international commerce and uphold the rules-based international order, and deter Iranian destabilizing activities in the region,” CENTCOM’s Army Gen. Erik Kurilla said in a statement. 

Developing: “Iran has arrested and detained a fourth U.S. national, further complicating the Biden administration’s efforts to secure an exchange of prisoners and lower tensions with Tehran,” Semafor reported Friday morning. 

The three Americans currently known to be in Iranian detention include businessmen Siamak Namazi and Emad Shargi and environmentalist Morad Tahbaz. It’s unclear just yet who exactly the fourth American is. Semafor points out, “Iran has long used hostage-taking as a tool of statecraft.”

Read more: 

• “Iran loses bid to host shipping event after vote at UN agency meeting,” Reuters reported Thursday from London; 
• And “Iran Is Breaking Out of Its Box: Washington Must Find New Ways to Counter Tehran’s Regional Influence,” Indiana University Professors Jamsheed and Carol Choksy wrote Thursday in Foreign Affairs. 

Welcome to this Friday edition of The D Brief, brought to you by Ben Watson with Bradley Peniston and Jennifer Hlad. If you haven’t subscribed to this newsletter yet, you can do that quickly here. On this day in 1995, the so-called “Third Taiwan Strait Crisis” erupted more than a month after Taiwan’s then-President Lee Teng-hui visited Cornell University in New York to deliver a speech about democracy. 

Pentagon chief Lloyd Austin will travel to the Pacific next week, with stops planned in Papua New Guinea (a first for a U.S. defense secretary) and Australia. “We've made groundbreaking progress toward our shared vision for a free and open Indo-Pacific over the past year, and I look forward to furthering our defense relationships,” Austin said on social media ahead of that trip, which will be his eighth to the region as Pentagon chief. 

Austin will also be dropping in on the United States’ largest-ever military exercise with Australia, Exercise Talisman Sabre. Eleven other nations are sending troops for the exercise, too, including Fiji, France, Indonesia, Japan, Republic of Korea, New Zealand, Papua New Guinea, Tonga, the United Kingdom, Canada, and Germany. Observers from the Philippines, Singapore, and Thailand will also attend. The drills will involve amphibious landings, ground force maneuvers, and air combat and maritime operations, beginning Saturday and ending August 4. 

The exercise will also feature the U.S. military testing wearable technology for its troops in the hopes of learning a bit more about heat stress and heat injuries. The devices measure “heart rate, heart rate variation, respiratory rate, pulse oxygen level activity, and a few other physiological metrics that all come together in order to enable a predictive algorithm to analyze the data from that service member and then alarm that individual, or squad leader, or medic to take a look at that person,” a program officer said this week. 

From the region: 

• “Inspired by Ukraine war, Taiwan launches drone blitz to counter China,” Reuters writes in a special report published Friday from Taipei; 
• “Taiwan probes alleged leak of classified reports, diplomatic cables,” Reuters reported separately Friday from the island; 
• And “Chinese hackers breached US ambassador to China's email account,” CNN reported Thursday; Politico has similar coverage. 

Meanwhile on Capitol Hill: Generals Brown, George advance to full Senate vote. The Senate Armed Services Committee on Thursday approved the two generals nominated by President Biden to lead the Air Force and Army—Air Force Gen. Charles Brown, Jr., who is currently the service’s chief; and Army Vice Chief Gen. Randy George. 

But Alabama Republican Sen. Tommy Tuberville is still blocking more than 250 officers from being promoted, claiming Wednesday night on the Senate floor that he’s doing so to protect “four to five thousand unborn babies” in protest of the U.S. military’s policy on abortion services and support for troops. So it’s unclear when Brown and George could even see a vote in the full Senate.   

Related reading: 

• “Tommy Tuberville May Cost Republicans Their Summer Vacation,” Newsweek reported Thursday; 
• “Schumer offers Tuberville abortion vote amid military blockade,” Politico reported Wednesday; 
• “Tommy Tuberville pledged to 'donate every dime' to veterans. He hasn't,” the Washington Post reported Wednesday; 
• “Ron DeSantis defends Sen. Tommy Tuberville's blockade on military promotions,” NBC News reported Thursday;
• And “Trump has 47% support among Republicans; DeSantis at 19%,” Reuters reported Wednesday. 

New: America’s disastrous war in Afghanistan offers several lessons for the ongoing war in Ukraine, according to analysts at the U.S. military’s watchdog agency the Special Inspector General for Afghanistan Reconstruction. SIGAR assembled the report at the urging of three Republican senators—John Kennedy of Louisiana, North Dakota's Kevin Cramer, Mike Braun from Indiana—as well as Arizona’s Kyrsten Sinema, an independent. 

Those lessons include: 

1. “The U.S. government struggled to develop a coherent strategy for what it hoped to achieve in Afghanistan and imposed unrealistic timelines that led to wasteful and counterproductive programs.”
2. “Lack of effective coordination—both within the U.S. government and across the international coalition—was a major obstacle to success in Afghanistan and resulted in a disjointed patchwork of ineffective efforts, rather than a united and coherent approach.”
3. “Though viewed as [America’s] greatest strength, the level of financial assistance in Afghanistan was often [the United States’] greatest weakness.”
4. “Corruption was an existential threat to the reconstruction mission in Afghanistan.”
5. “Building and reforming the Afghan security forces was hindered by their corruption, predation, and chronic dependency on the United States.”
6. “Tracking equipment provided to Afghan security forces proved challenging well before the government collapsed.”
7. “Monitoring and evaluation efforts in Afghanistan were weak and often measured simple inputs and outputs rather than actual program effectiveness.” 

Most of these arguments will be perhaps painfully familiar to Defense One readers as well as Afghan war veterans. Indeed, many of the points were raised in our most recent podcast on that conflict, “The legacy of America’s Afghan war, with Elliot Ackerman,” as well as several previous episodes, including “10 trips to Afghanistan, with Kevin Maurer.” Read more about each of SIGAR’s seven points in its full report (PDF), here. 

Extra reading: 

• “How a Tiny Archipelago Gave Russian Ships a Foothold in the Atlantic,” the Wall Street Journal reported Friday on Denmark’s Faroe Islands, located halfway between the UK and Iceland; 
• “Poland to move soldiers to east of country due to Wagner risks,” Reuters reported Friday from Warsaw; 
• And “Weapons Sent to Ukraine Were in Danger of Falling into Criminal Hands, Watchdog Warned,” Military.com reported Thursday after using a Freedom of Information Act request to obtain a Pentagon inspector general report from 2022 covering the opening months of Russia’s Ukraine invasion. 

And lastly today: The “Good Luck Flag” carried by a Japanese soldier during WWII is being returned to his family. The white flag, emblazoned with the Rising Sun and signed by Shigeyoshi Mutsuda, his family and friends, was displayed for decades at the USS Lexington Museum in Corpus Christi, Texas. After one of Mutsuda’s sons recognized his father’s signature, the museum arranged to return the flag to the family, the Associated Press reported Thursday.

About 500 such flags have been returned over the decades, many through a nonprofit organization called the Obon Society. AP has a bit more, here.