Moscow’s mis-assessment has cost Russia billions of dollars, resulted in hundreds of thousands of Russian causalities, and cratered parts of the Russian economy. Putin might not have attacked if he had accurately anticipated the significant struggle that would ensue. But the West’s miscalculation almost certainly delayed critical military assistance and reduced the potential for NATO member states to do more to strengthen Ukraine’s defense at the outset.

As the world observed Russia preparing to invade Ukraine in early 2022, the most common prediction across the U.S. national security community was that the Russian military would overwhelm the Ukrainian defenders in short order. Russia’s 900,000 active-duty personnel, 2 million reserve forces, and $45 billion defense budget dwarfed that of Ukraine, which had an estimated 196,000 active-duty troops, 900,000 reservists, and defense spending one-10th that of Russia at the time of the invasion. By one account, Gen. Mark Milley, then-chairman of the Joint Chiefs of Staff, privately predicted to members of Congress that Ukraine would “ fall in 72 hours .” It appeared likely that the world would witness the first conquest of a European nation since the end of World War II over 75 years ago.

As the world observed Russia preparing to invade Ukraine in early 2022, the most common prediction across the U.S. national security community was that the Russian military would overwhelm the Ukrainian defenders in short order. Russia’s 900,000 active-duty personnel, 2 million reserve forces, and $45 billion defense budget dwarfed that of Ukraine, which had an estimated 196,000 active-duty troops, 900,000 reservists, and defense spending one-10th that of Russia at