From a front-page New York Times news article about the entry into the presidential race of Governor Scott Walker, Republican of Wisconsin:
his repeated comments that the most important foreign policy decision of his lifetime was President Ronald Reagan's firing of air traffic controllers in 1981, because it got the attention of the Soviet Union, was a sign to some Republicans that Mr. Walker, who dropped out of Marquette University and has not traveled widely abroad, has a limited worldview.
From The Education of Ronald Reagan: The General Electric Years and the Untold Story of His Conversion to Conservatism, by Thomas W. Evans:
The PATCO incident had consequences outside of the narrow labor area. As a top White House aide commented in an oral history interview years later, "I think what is extraordinary about it is the impact it had way beyond domestic politics. Especially when you listen to George Shultz or Henry Kissinger talk about the impact it had on foreign policy, it was stunning. Basically the impact was that [foreign leaders] said, 'Oh my God, this President took on the unions and did it. He might do other things.' Which was true, of course."
Evans footnotes that to an oral history interview with Reagan aide Martin Anderson.
Peggy Noonan, who also worked for Reagan, has also written about this: "Reagan's secretary of state George Shultz said that the Patco decision was the most important foreign-policy decision Reagan ever made."