The British Army must act rapidly to prevent any further military action by President Vladimir V. Putin of Russia beyond the borders of Ukraine, the force’s new head said on Tuesday, adding that Britain must be ready to defend NATO territory if necessary.
“This is our 1937 moment,” the military leader, Gen. Patrick Sanders, said, making reference to Western Europe’s failure to confront Nazi Germany’s territorial expansion in the years preceding World War II. “We are not at war,…