I think we should cut all those countries loose from our obligatory defense, and have them arrange their own defense.
South Korea, Japan, the Phillipines, Australia, New Zealand, Taiwan... not one of them would come to our aid, or even allow our nuclear vessels to port in their nations. So open treaties to defend these nations are liabilities that obligate us to wars in their defense, with no upside for the U.S., of them ever potentially coming to our aid if the U.S. were attacked.
We can always choose to aid them, but should not be obligated by treaty to do so.

Similarly, eastern Europe. It is not our place to defend eastern Europe, let alone make former Warsaw Pact and Soviet nations members of NATO. That's just pissing in Russia's face, and partly explain's Russia's increasing hostility toward us in recent years. Since 1991, we've taken advantage of Russia's weakness and expanded our military presence on their border, that to Russian hardliners is a clear threat to their security.
We should let Russia manage its "near abroad" as they term it, as we would want no one else in our hemisphere. The former Soviet states are their own territory, their own Monroe Doctrine sphere of influence, and we should back off from it and improve relations with Russia, if it is not already too late for that.

We should be committed to defend the Western Hemisphere, and that's it.

All these other alliances are obligations to costly wars, if any incident occurs. They have been obsolete alliances since the Cold War, and should have been dropped at that point. We can always elect to go to war if it's in our national interest. We shouldn't be obligated to, no matter how provocative the action by our allies. Again, with the examples of Poland, Latvia, Estonia and Lituania, Rumania, Hungary and others as NATO members, with Europe considering Georgia and Ukraine for similar NATO status. Gee, why should that upset Russia?
It's as if Russia gave Mexico and Cuba Warsaw Pact membership. NATO expansion is a provocative threat in their own back yard. Georgia being the prime example. If Georgia was a NATO member in August 2008, we would be supremely fucked right now. Like the war guarantee to Poland in 1939, that would obligate us to an unnecessary war, not in our interest, where ultimately everyone, including us, loses.