"The most famous example was the 1974 Foreign Relations Act. Passed in the wake of Watergate scandal, the congressional resolution cut off all military assistance to the South Vietnamese government. But that pubic stand-down only encouraged the North Vietnamese communists to violate the Paris peace accords and renew the war—without any more worries of U.S arms shipments or air strikes.
The Neutrality Acts of the 1930s, passed by an isolationist Congress, forbade U.S. military assistance to, or trade in war material with, any belligerent, regardless of whether they were aggressors or victims. Such actions of “conscious” only emboldened Nazi Germany, Italy, and Japan to attack democracies and other neutral states. Hitler, Mussolini and Tojo were convinced that whatever their provocations, the United States had no stomach to stand up to any of them, or even to join Britain and France in a united front of resistance. World War II with its 50 million dead followed.
Often even mere assurances of restraint by American officials, that suggest either inaction or weariness, have had the same effect as congressional resolutions in assuring interested observers that the United States would either not act in the face of aggression—or tire more quickly of ongoing fighting than their our enemies.
In a routine policy address Cold War warrior and Secretary of States Dean Acheson once warned the communist bloc that the American defensive perimeter in the Pacific went from Aleutians to Japan to the Ryukyus and onto the Philippine Islands. But Acheson, perhaps inadvertently, left out the Korean Peninsula. Many argued at the time that this omission gave the green light for the communists to invade South Korea in 1950 on their erroneous assumption that the United States would not intervene in an area outside its sphere of influence. Three years and hundreds of thousands of war dead followed.
Jimmy Carter had a far worse habit of telegraphing his intention to enemies. In 1977 he declared that America had outgrown its “inordinate fear of communism”. But by that time, global communism from Stalin to Mao had killed nearly 100 million of its own and invaded dozens of natural countries. Nothing “inordinate” about that.
So next when Carter made it clear that he would not retaliate immediately against Iran for storming of the US embassy in November 1979, it was not much of a surprise that the Soviet Union quickly invaded Afghanistan—unafraid of an America that wouldn’t use force to free its own diplomats or punish those who took them.
In a July 1990 in a meeting with Saddam Hussein, then American ambassador Arpil Glaspie purportedly assured the Iraqi government that “ we have no opinion on the Arab-Arab conflicts, like your border disagreement with Kuwait.” Saddam attacked Kuwait a little more than a week later."