Along with Abdel Karim Qasim and other Iraqi military officers, Arif was a member of the clandestine organisation, the Free Officers of Iraq. Like Qasim, Arif served with distinction in the otherwise unsuccessful 1948 Arab-Israeli conflict, where he captured Jenin in what is now the West Bank part of Palestine. During the summer of 1958, Prime Minister Nuri as-Sa'id ordered Iraqi troops under Arif to aid Jordan, as part of an agreement of the Arab Federation. Instead, however, he led his army units into Baghdad and on July 14 launched a coup against the Hashemite monarchy. Qasim formed a government under the newly proclaimed republic and Arif, his chief aide, was appointed deputy prime minister, interior minister, and deputy commander-in-chief of the armed forces.