Security has been beefed up at public and diplomatic buildings in Spain following a string of letter bombs, including one that injured an official at the Ukrainian embassy in Madrid. As per the nation's interior ministry on November 24th an "envelope with pyrotechnic material" addressed to the Prime minister was disarmed by them. The Ukrainian embassy, military equipment firm Instalaza, and the defence ministry all received three similar devices. Early on Thursday morning, a fifth one was detected at Spain's Torrejon de Ardoz air base.