[WayneS]

It has definitely stopped being the case. Especially today, when an ICBM can travel half-way around the world in a couple of hours.

Even at the start of World war II, the Japanese were not impeded in any way by the Pacific Ocean when they launched a surprise attack on one U.S. territory, and a surprise invasion of another U.S. territory.

It is clear to me that our “moats” are no longer an adequate first line of defense, and that they have not been for quite some time.

[Colonel Kangaroo]

I believe that an argument can be made that modern weaponry makes non-intervention an even more appealing path for the US. The big moats are still effective in preventing the invasions that threaten continental powers, so our military efforts need only be concerned with strategic defense. The power projection desired by interventionists only increases the incentive of others to attack us. Not only does drawing back save money, the lessened offensive threat to other nations means that measures of strategic defense, like an ABM system against rogue states, will not be as likely to be seen as a destabilizing threat to others.