During the Cold War Republicans presented themselves as the Daddy Party, prepared to defend America in a dangerous world. They won an enduring electoral advantage on international issues.
But the GOP lost that advantage with the end of the Cold War. The world is still dangerous, but not so much to America. Terrorism is a monstrous crime that frightens, but it does not pose an existential threat. And the United States far outranges any other power or group of powers militarily.