May 8 (UPI) -- Britain will sanction a Russian shadow fleet of up to 100 tankers on Friday, as European leaders gather in Oslo for a military meeting where they will seek to exert extra pressure on Moscow's economy to further empty its war chest. Prime Minister Keir Starmer is expected to announce the sanctions against the tankers at the Joint Expeditionary Force meeting that London said are the core of President Vladimir Putin's shadow fleet, which has carried more than $24 billion worth of