washington — Reports that billionaire Elon Musk has held multiple calls with Russian officials, including President Vladimir Putin, should be investigated by the Pentagon and law enforcement agencies on national security grounds, two senior Democratic senators said in a letter seen by Reuters on Friday. Musk, who has been appointed to a senior government role by Republican President-elect Donald Trump, oversees billions of dollars in Pentagon and intelligence community contracts as CEO of aerospace company SpaceX. Senator Jeanne Shaheen, a senior Foreign Relations Committee member, and Senate Armed Services Committee Chair Jack Reed told U.S. Attorney General Merrick Garland and