Who is a “U.S. person” in the eyes of the IRS?

According to the IRS website, a U.S. person  is any of the following:

• A U.S. Citizen, which is anyone with a U.S. passport,
• A Green Card holder, or
• A U.S. resident – U.S. resident is a term used to describe someone who spends more than 183 days in the U.S. under the Substantial Presence Test. U.S. residents are also commonly referred to as resident aliens.