Reporting Your Income(p27)

You must report each item of income that is taxable according to the rules in chapters 2, 3, and 4. For resident aliens, this includes income from sources both within and outside the United States. For nonresident aliens, this includes both income that is effectively connected with a trade or business in the United States (subject to graduated tax rates) and income from U.S. sources that is not effectively connected (subject to a flat 30% tax rate or lower tax treaty rate).