Barack Obama has arrived in Europe for The Nuclear Security Summit at the Hague . Only last December , law enforcement authorities in Mexico discovered a vehicle believed to have been stolen by thieves which contained radioactive medical materials that could have been used to power a dirty bomb . An emergency G7 summit on the Ukraine crisis will be held on the sidelines of the nuclear summit . Andrew Hammond says Obama will seek to find consensus on new sanctions against Russia . Obama sees enhancing global nuclear security as a key part of his legacy , Hammond says .
Barack Obama has arrived in Europe for The Nuclear Security Summit at the Hague . An emergency G7 summit on the Ukraine crisis will be held on the sidelines of the nuclear summit . Andrew Hammond says Obama will seek to find consensus on new sanctions against Russia . Obama sees enhancing global nuclear security as a key part of his legacy , Hammond says .