Meanwhile, the Radicals continued Argentina's neutrality policy during World War I, despite the United States urging them to declare war against the Central Powers. Neutrality enabled Argentina to export goods to Europe, in particular to Great Britain, as well as to issue credit to the belligerent powers. Germany sank two Argentine civilian ships, "Monte Protegido" on April 4, 1917, and the "Toro", but the diplomatic incident ended only with the expulsion of the German ambassador, Karl von Luxburg. Yrigoyen organized a Conference of Neutral Powers in Buenos Aires, to oppose the United States' attempt to bring American states in the European war, and also supported Sandino's resistance in Nicaragua.