In the apostasy campaigns the Jews secretly aided the apostates, and incited the tribes who had accepted Islam to apostatize. The designs of the Jews were frustrated, and the apostasy campaigns ended in victory for the Muslims. Then under Abu Bakr and Umar the Muslims embarked on a campaign of conquests. Within a short time the Muslims were masters of Iraq, Persia, Syria and Egypt. That alarmed the Jews. The Jews were now no longer in the position to come in direct confrontation with the Muslims. They therefore changed their strategy, and instead of a direct attack on Islam they resorted to a campaign for the subversion of Islam from within.