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Britain made last minute efforts on Tuesday to tighten security measures for the funeral of former Prime Minister Margaret Thatcher on Wednesday.
This, after the twin bombing of the Boston Marathon, which left three people dead and more than 170 injured, several critically.
Police in some major U.S. cities were monitoring landmarks, government buildings, transit hubs and sporting events.
Law enforcement agencies also urged the public via Twitter and Facebook to report suspicious activity to the police.
Russian sports officials also said that they will be beefing up security in preparation for the Winter Olympics and other events.
