There are limits to how much such developments can be understood in terms of historical lessons being applied. But it is true that American policymakers have used "Munich" as guidance on when it is necessary to go to war, and "Vietnam" as guidance on when to restrain from going to war.
Both will continue to be powerful influences on policy. And they also influence the debate over the "lessons of Iraq". Just this week on his first visit to Vietnam, Bush the Younger declared the lesson of Vietnam that should be carried over to the Iraq War is, "We'll succeed unless we quit". This is why it's important for opponents of the Iraq War to understand how pervasive the Weinberger-Powell Doctrine had become in the military and in Congress prior to the 9/11 attacks.
Many of the former generals and military analysts now criticizing the Iraq War are doing so from the implicit assumption of the Weinberger-Powell Doctrine that the military should be concerned with conventional war and nuclear war, but not guerrilla war ("low-level conflict" in Pentagonese). Their goal is to return to a condition where the military establishment is lavishly funded and military contractors generously compensated, but without anything so messy as actually military operations being required.
What we really need at this point is a new orientation in military affairs - one different from the current tech-centric "revolution in military affairs (RMA)". On the one hand, most cases in which the US might be required to intervene militarily in the coming decades are likely to look far more like the current Iraq War and Afghanistan War than like the Gulf War of 1990 or Reagan's spectacular tirumph over the mighty military colossus of Grenada in 1983. So preparation for counterinsurgency and national-building are vital.
On the other hand, the US doesn't need to be looking for guerrilla wars to poke our noses into. Ultimately the only way to avoid that is to have responsibile people controlling the Presidency and Congress. But it's also important to remember that there's no institutional mechanism that can always prevent that. So there should be an emphasis on "right-sizing" our military so that i can be prepared to deal with likely threats but also to minimiz the temptation to the Dick Cheneys and Rummys of the world to undertake foolish military adventures.
Record's book also reminds us that it's important to look carefull at the historical experiences of war and not settle for the lazy assumptions that become ossified into the conventional wisdom. He concludes:
Whatever the utility of reasoning by historical analogy as a tool of policy formulation and implementation, it is clear that policy makers will continue to be influenced by past events and what they believe those events teach. It is also clear that presidents' knowledge of history varies widely, and that reasoning by historical analogy is but one of a host of factors at play in presidential decision making. Presidents Theodore Roosevelt, Woodrow Wilson, Harry Truman, and John Kennedy were well read in history, whereas presidents Lyndon Johnson, Ronald Reagan, and George Bush [the elder] displayed considerably less knowledge of history. Moreover, in analyzing a specific presidential use-of-force decision it is virtually impossible to determine the exact influence of reasoning by historical analogy in relation to such other factors as presidential personality, domestic political considerations, and the role of key advisers. Munich clearly weighed heavily on the minds of Truman in 1950, Johnson in 1965, and Bush in 1990, as did Vietnam on the mind of Clinton in the 1990s. But all the evidence suggests that, for better or for worse, some thinking about history attends all significant presidential uses of force, especially those that invite war.
For more on the Weinberger-Powell doctrine, see the following articles made available at GlobalSecurity.org:
The Weinberger Doctrine In The Post-Cold War Era by Major Colin F. Mayo, USMC (1992)
Beyond The Weinberger Doctrine by Major Scott T. Campbell USMC (1995)