President Biden on Wednesday announced that the U.S. will send Ukraine 31 advanced M1 Abrams battle tanks, following Germany's decision to supply Kyiv with at least 14 Leopard 2 tanks and Britain 14 of its Challenger 2 tanks.  Retired U.S. Lt. Gen. Mark Hertling, a former tank commander and head of U.S. forces in Europe, told CNN that once you add in other donated Leopard tanks from Europe, Ukraine will probably get 100 to 150 German-made battle tanks within two to three months, followed by the 31 Abrams in six to eight months. Will that really help Ukraine? Ukraine had requested more Western tanks, and quicker, but even dozens of Leopards and Abrams tanks could make a difference on the battlefield, Hertling said. "Tanks are used primarily for tactical offensive operations: shock action, rapid maneuver, lethal firepower," and serious intimidation. "These tanks are not suddenly going to turn up overnight and radically change the battlefield," Nick Paton Walsh told CNN. But this announcement by the U.S. and Germany "does do one important thing: It tells those in Moscow planning the months ahead that they have a very small window until Ukraine's weaponry gets incrementally and enormously better in its quality, and that is something I'm sure what will be weighing on the morale of those in Russia's military." The commitment of Western tanks is "hugely significant," both "symbolically" and "substantively," former CIA director and retired Gen. David Petraeus told CNN. "On the battlefield, the tank is the centerpiece of combined arms operations, which is what will be necessary to have successful offensives" and reclaim territory, he explained. "That tank is the piece around which everything else will be built" — infantry fighting vehicles, artillery, air defense, engineers, electronic warfare, mine-sweepers, drones — and combined, these Ukrainian formations can pack "a very powerful punch, and it could enable them to break through in some key areas," like severing the supply lines from Russia to Crimea.  Russia knows this is coming, but "I don't really expect them to try to counter it," retired U.S. Gen. Philip Breedlove, former NATO Supreme Allied Commander in Europe, told NBC News. The Russians are stuck in their old artillery-heavy, infantry-sacrificing "ground-and-pound" warfare, and "I don't really expect that they'll make a lot of changes" at this point. "Russia sent an awful lot of tanks into northern Ukraine, and a bunch of them got killed, and they didn't change the shape of the battlefield because they weren't employed well," he added. With the Leopards and Abrams tanks, plus the more agile Bradley and Stryker armored infantry carriers, "what we're putting together is an armored team that can survive on the battlefield" and change "the shape and nature of the battlefield."