By Simon Lewis and Ingrid Melander BRUSSELS (Reuters) -NATO on Friday rejected Ukrainian calls for help to protect its skies from Russian warplanes, wary of being dragged into Moscow’s war on its neighbour, but Europe promised more sanctions to punish Russian President Vladimir Putin. Ukrainian President Volodymyr Zelenskiy had appealed to NATO to declare a no-fly zone over his country, which Russian forces invaded by land, sea and air on Feb. 24. “We are not part of this conflict,” NATO Secretary General Jens Stoltenberg said in denying Ukraine’s request. “We have a responsibility as NATO all…