Nobusuke Kishi [Abe's grandfather] did became PM in Japan around late 50s to 60s. Even though he's a outright war criminal, the NATO need a strong allies in East Asia, so Kishi a very anti communist politicians was put to power, he ratified the Treaty of Mutual Cooperation and Security between the United States and Japan  with US, expanding Japan rights to defence itself and strengthen the JSDF. This again sparkled mass protest by the Japan leftist, communist and general public as they fear Japan may go to war again.