Opening a U.S. LLC takes a day and costs little. That is why it is the first entity many people abroad set up. The problem is not the LLC itself but what happens when the owner lives in another country.
Three things that change
First, a single-owner foreign LLC has its own annual information return, with a steep fixed penalty for missing it. Second, depending on the activity, the owner may have to file personally in the U.S. Third, the owner's home country may not treat the LLC as transparent and may tax the profits differently.
The right question
It is not LLC or corporation, but: how will profits leave the U.S. and at what combined rate? That answer decides the structure. Sometimes the LLC is perfect. Sometimes a corporation with a clear dividend policy costs less overall.
If you already have an LLC and live outside the U.S., a thirty-minute review is worth it.