BTW, if someone wants fly to Holland to smoke pot they'll have to remember that it's actually illegal to do so, even though it's openly tolerated by the Dutch government. But they can still be busted for it there, and they can be busted for it when they get back home, if the US AG has the evidence.
Now for the real question - what the hell have *you* been smoking?
If you commit a crime, you can only be tried and punished for it in the jurisdiction in which the crime occurred. If you, a private citizen of the US, go to the Netherlands, commit a murder there, then return to the US, you can NOT be tried for that crime in the US. At most, you can be arrested by US authorities, and sent to the Netherlands to stand trial (whether or not this is the case depends on what extradition treaties, if any, exist between the US and the Netherlands).
(note that the rules are somewhat different if you are an active duty serviceman - the military has automatic jurisdiction over all criminal acts of active duty personnel, regardless of where those acts occurred)
Now if you were in the Netherlands, and you hired a hit man to kill someone in the US, you could potentially be tried and convicted in a US court - under the "accessory before the fact" and "conspiracy" concepts, you are as guilty as the actual killer, even if you were on another continent when the crime was committed.
*That* is the basic theory underlying the trials of those captured in Afghanistan - they were involved in the planning of attacks against US targets, and as such the US should have jurisdiction over them.
And finally - smoking pot isn't illegal *anywhere* in the US. The laws all revolve around cultivation, possession, sale, etc. The only criminal penalties for using are the "driving under the influence" laws if you get caught driving while stoned.