It’s not Ronald Reagan’s GOP anymore. The Republican Party’s shift from Russia hawk to something softer is straining the GOP at a crucial juncture, highlighting the ascendency of former President Trump’s “America First” approach and exasperating old-guard conservatives who long for a return to the assertive foreign policy championed by the party through generations prior. It’s created nothing short of an identity crisis for those Republicans who still identify with the party of former President Reagan, a Cold War president long lionized within the GOP ranks for his aggressive confrontations with the Soviet Union. “Ronald Reagan would not recognize today’s...