LONDON (Reuters) - Britain s interior minister said a claim by U.S. President Donald Trump that the culprits behind a bombing on a London train were in the sights of the police, made on Twitter shortly after the attack, had been nothing more than speculation.  It s never helpful to have speculation about an ongoing operation and I would include the president of the United States in that comment,  Amber Rudd told BBC television on Sunday.  It is pure speculation, absolutely.  Rudd s comments echoed those of British Prime Minister Theresa May who said on Friday it was not helpful for anyone to speculate on investigations. 