The question is based on a false premise. Countries should mind their own business and stay out of foreign entanglements.
A true libertarian doesn't believe the government should be for hire. Everyone ought to be protected equally, and no one should be able to buy special treatment or favors from the government.
The world would be a much better place if Europe had kept out of foreign entanglements a few hundred years ago.. the native peoples might still have their own countries!
How does small government result in everyone being protected equally? Surely with less government involvement those who can afford it will have better protection (maybe not militarily, but financial, health and otherwise) than those who are less well off?
I agree, no one should be able to buy favours from the Government. How do you stop that? Outlaw lobbying? State funding of political parties? (So parties aren't influenced by donors.) A wholly elected government? (So guys like Donald Rumsfeld can't be appointed.)
Here MPs have to declare any payments and gifts (checkable by anyone online). Do you have that in the US? Does it apply to people appointed by the President as well as elected representatives?