By Howard Schneider and Jonnelle Marte (Reuters) – U.S. Federal Reserve officials on Thursday began taking stock of how the unfolding conflict in Ukraine might influence the economy and their planned shift to tighter monetary policy, with investors and some officials suggesting it could slow but likely not stop a planned round of interest rate increases. Oil and commodity price shocks and a possible blow to global growth and confidence were clear risks, analysts said, and one Fed policymaker said the events of the last 24 hours could weigh on upcoming Fed decisions. “The implications of the un…