The U.S. Insulation Policy did not keep the U.S. out of WW1. Well, had the U.S. cut off all trade to avoid damage and death in their Ships sailing the high seas, maybe yes......
Neither did it keep the U.S. out of WW2. Well, self to blame, for the U.S. had been fiddling with the politics in the far east. Japan attacked, and Hitler declaired war on the U.S. (seeing that inevitably they would become allies with the Brits against the Japanese)
So, there may be a point there. Although the U.S. had a passive policy and declaired themself neutral, they still had their fingers all over the world, - the "passive" policy was never properly put to the test.
So, sever all foreign connection to the US. Dock the ships, seal the airports, cut off all trade and be your own masters.
Wonder how that's gonna help you from someone that wants to pick a fight with you though..............