Strict libertarians are for open borders and offshoring manufacturing too, but they are a mere fly in a sea of progressive ointment.
Libertarianism can only function within nationalism, which is what the Founding Fathers set up with America.
Those who are international libertarians are simply people who want to profit over the desperation of other people. They don’t really believe themselves that you can have a functional society on an international level. If I complain about not being paid enough to pay my rent and buy food, they can fire me without consequence and bring somebody in who won’t complain.
International libertarianism is just a fraud, like socialism.
International libertarians tend to be really fascists, because they want to show that all that happens, when people are free, is that evil people take over and drive suffering. So, the only way to counterbalance the tendency of libertarianism to turn evil is to have a strong government put a stop to it.