He was brought to office as a Vice-Premier and Minister Secretary of State (Minister without portfolio), in a War Cabinet headed by the PNL's leader Brătianu, serving between July 1917 and January 1918. According to Xeni, Ionescu's advocacy of an Entente alliance had made him the target of intense criticism, at a time when the territory still controlled by Romanian authorities was suffering major hardships, and replied that "war had to be made". At the same time, he and the premier agreed on the principles of electoral and land reform to be carried out in a future Romania, as the Conservatives appeared destined to lose appeal.