Germany plans to postpone the closure of the country’s last three nuclear power plants as it braces for a possible shortage of energy this winter after Russia throttled gas supplies to the country, said German government officials. Mr. Scholz hinted at the decision last week, saying for the first time that it could make sense to keep Germany’s last three nuclear reactors online. Mothballed coal plants have already been brought back online to prevent energy blackouts after Russia slashed gas supplies in June, a decision that will complicate Berlin’s plans to cut greenhouse-gas emissions and reduce air pollution.