There are other elements at work as well, which are briefly discussed, but the idea of spreading liberal Western democracy around the world is the theory and public justification behind all these Middle-Eastern conflicts in which we find ourselves (I say that understanding that there were other reasons why these conflicts began, but Afghanistan, for instance, long left behind the war based on punitive reasons and into the nebulous area of "nation building" and "winning hearts and minds").
Now, under Trump, it appears that both the U.S. and U.K. policies of never-ending wars is about to change.
However, based on the inclusion of the invasion of Panama in 1989, I think that Black Pigeon has misinterpreted or is unaware of the source of the policies that led our lest several presidents, and which have been rejected by Trump.
In 1989, Francis Fukuyama published his highly influential essay, "The End of History?" in The National Interest. His ideas were later expanded and embellished in his 1992 book, The End of History and the Last Man. To Fukuyama, we were approaching the end of history, so to speak, because all competitors to Western liberal democracy had failed. Thus, although there were to be continued conflicts, the arch of history was that eventually all peoples and nations would adopt the Western liberal democratic ideals.
Combined with this was the idea--and I don't know the source of the theory, but do note that the clearest articulation was from George Friedman--that the U.S. had reached a point in its power and influence where it no longer needed to win wars, but it was sufficient to disrupt one's enemies.
These two ideas underpin the foreign policy of every president from George Bush (Sr.) through Obama. It was these ideas that informed the policy makers that believed that if you could just introduce democracy the result--magically--would be a democracy styled after the Western liberal tradition and friendly toward the United States and the West. And if it didn't work out that way, just stir the pot until it finally did work.
The counter-theory to this was Samuel P. Huntington's theory of the clash of civilizations, first articulated in an 1992 lecture, followed by a 1993 article entitled "The Clash of Civilizations?" published in Foreign Affairs, and more thoroughly fleshed out and explained in a 1996 book, The Clash of Civilizations and the Remaking of World Order. Huntington's thesis was intended as a response to, and rejection of, Fukuyama's thesis. Huntington saw the 21st Century as unfolding as one where shared values and identities would draw together nations from the same civilizations, and inform and influence conflict (including wars) between differing civilizations. Thus, for instance, where Fukuyama predicted that democracy would spread through the Middle-East as the tyrants fell, Huntington saw Islam turning to its roots in their version of the Western Christian Reformation, and striking out at surrounding civilizations.
Obama, the Clinton's, and the Bush's clearly fell within Fukuyama's camp. Based on reports I have seen, Trump and his advisers have, instead, accepted Huntington's model. Thus, the dramatic shift Trump is attempting. Whether it succeeds, or not, is not clear. Progressives of all stripes (liberals and neo-cons) are deeply committed to the The End of History and the American empire it promises.
And as for the Panama invasion. It was too soon following Fukuyama's article to be influenced to any great degree. And while there was regime change, it was because of Noriega's ties to the international cocaine cartels and smuggling, and his aggressive and provocative acts against U.S. forces serving in the Canal Zone. He was tugging on Superman's cape, to borrow an analogy. The consequence of the invasion (if you can call it that) was the arrest and extradition of Noriega for trial, and no real attempts at "nation building."