As of the Dec. 15 deadline, 97.9% of active duty soldiers in the US Army have received at least one Covid-19 vaccine, slightly trailing 98% of the Navy but slightly higher than the Air Force (97.5%) and the Marine Corps (95%). The Air Force discharged 27 airmen who had refused to get the shot and the Navy has fired one sailor for refusing to be tested while he was pursuing an exemption.

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A drone that can select and engage targets on its own attacked soldiers during a civil conflict in Libya.Why it matters: If confirmed, it would likely represent the first-known case of a machine-learning-based autonomous weapon being used to kill, potentially heralding a dangerous new era in warfare.Get market news worthy of your time with Axios Markets. Subscribe for free.Driving the news: According to a recent report by the UN Panel of Experts on Libya, a Turkish-made STM Kargu-2 drone may have "hunted down and ... engaged" retreating soldiers fighting with Libyan Gen. Khalifa Haftar last year.It's not clear whether any soldiers were killed in the attack, although the UN experts — which call the drone a "lethal autonomous weapons system" — imply they likely were.Such an event, writes Zachary Kallenborn — a research affiliate with the Unconventional Weapons and Technology Division of the National Consortium for the Study of Terrorism and Responses to Terrorism — would represent "a new chapter in autonomous weapons, one in which they are used to fight and kill human beings based on artificial intelligence."How it works: The Kargu is a loitering drone that uses computer vision to select and engage targets without a connection between the drone and its operator, giving it "a true 'fire, forget and find' capability," the UN report notes.Between the lines: Recent conflicts — like those between Armenia and Azerbaijan and Israel and Hamas in Gaza — have featured an extensive use of drones of all sorts. The deployment of truly autonomous drones could represent a military revolution on par with the introduction of guns or aircraft — and unlike nuclear weapons, they're likely to be easily obtainable by nearly any military force.What they're saying: "If new technology makes deterrence impossible, it might condemn us to a future where everyone is always on the offense," the economist Noah Smith writes in a frightening post on the future of war. The bottom line: Humanitarian organizations and many AI experts have called for a global ban on lethal autonomous weapons, but a number of countries — including the U.S. — have stood in the way.More from Axios: Sign up to get the latest market trends with Axios Markets. Subscribe for free

Because fatigue can corrode mission performance, a new physical training manual tells soldiers to grab 40 winks when they can, part of a new holistic approach to health in the ranks.

Senator Kirsten Gillibrand has fought for years to remove commanders from deciding assault cases. Now, more colleagues and a Pentagon panel agree.

In an important test, the ARRW missile didn't launch from the B-52 bomber carrying it.

Russia is amassing unprecedented military might in the Arctic and testing its newest weapons in a region freshly ice-free due to the climate emergency, in a bid to secure its northern coast and open up a key shipping route from Asia to Europe.