The Pentagon has taken a step back from supporting research and development of robotic land vehicles. The goal was to be able to move firepower on the front lines without risking the lives of tank operators.

Recently, setbacks to tank operators in the Ukraine conflict, on both sides, have sidelined any major combat use of tanks. Changes on the battlefield have led to heavy tank losses of Russian and Ukrainian tanks in combat.

Drones, air launched mines, anti-tank weapons such as the Russian Kornet and the US Javelin (and many others), have slowed down tank assaults and forced tank operations mostly into hide and seek operations.

Modern tank warfare was largely invented by the Germans, starting in the 1930s. Heinz Guderian is credited with what were known as Panzer tactics and the use of blitzkrieg to rapidly gain ground against an enemy. His book, Achtung-Panzer! (1937) outlined a new type of organization featuring tanks and a motorized corps capable of rapid movement in the battle area.

The theories were put into practice in World War II to good effect. The idea was revolutionary: instead of the use of armor to support infantry, armor and infantry were both mobile and integrated for the first time. Eventually, the German Panzer Gruppe formula formed the foundation of Soviet (now Russian) and US (and allied) approaches to armor warfare.

The problem in Ukraine is that massing tanks is an invitation to disaster as modern weapons, including drones, make now-classical tank warfare operations difficult, inviting heavy losses impacting not only hardware but also manpower. Skilled tank operators are in short supply.

The Defense Department was so suitably alarmed by the changes on the battlefield in Ukraine that a major upgrade of the Abrams main battle tank was canceled. The Pentagon said that it would develop a new version of the Abrams, one that incorporated lessons learned. Exactly what the new tank will look like, and why it would be any better than its predecessors, we do not know.

The Abrams tank proved to be a beast to operate and support in Ukraine. It is a very heavy and fat tank, and it became even heavier and more ungainly after the Ukrainians welded on layers of reactive armor, lifted from deceased Russian T72s, and built iron cages to help protect the turret and engine compartment from anti-tank weapons and drones.

Even so, two thirds of the Abrams tanks shipped to Ukraine have been destroyed or disabled, and a handful of them have ended up in Russia both as trophies and for exploitation. The German tanks, different versions of the Leopard marketed by German industry as better than the Abrams, ended up the same way: Neither the US nor the German-made tanks were wunderwaffen.