By Allison Lampert and David Shepardson (Reuters) – European nations and Canada moved on Sunday to shut their airspace to Russian aircraft, an unprecedented step aimed at pressuring President Vladimir Putin to end his invasion of Ukraine, the biggest attack on a European state since World War Two. The United States is mulling similar action, but has yet to make a final decision, according to U.S. officials. The ban on Russian jets comes as the airline industry continues to grapple with the fallout from the COVID-19 pandemic that is still undermining global demand for travel. Germany, Spain and…