From May 1919, the Romanian Army began moving into the eastern Banat. Roth was captured during the Hungarian–Romanian War, and held in custody by Romania to 1920. During this interval, the Banat was effectively partitioned between Yugoslavia and Romania, with Timișoara going to the latter. Constantin Argetoianu, who served as Minister of Internal Affairs, publicly accused Roth of maintaining a seditious correspondence with Budapest, and announced that its publication would uncover a ring of Hungarian irredentists in the Banat. This group, Argetoianu claimed, had been instructed to canvass votes for the Socialist Party of Romania. As argued by Brînzeu, Roth's release came once he formally promised to Artur Văitoianu, the Prime Minister of Romania, that he would not engage in any form of politics. Argetoianu claimed to have personally decided for releasing the "communist ex-president of Timișoara Republic", whom he had previously called a "Hungarian government commissar". Upon his release, Roth remained Argetoianu's devoted friend for at least two decades.