I am a naturalized US citizen with a valid passport and I've heard rumors that trying to reenter the United States from the Philippines requires a naturalization certificate as well as the valid passport are these rumors true?
Definitely not true. A U.S. passport is enough.
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All U.S. citizens, including children, must present a passport or other approved travel document when entering the U.S. by air. U.S. citizens can present a passport, a NEXUS card at airports with a NEXUS kiosk, a U.S. military ID with travel orders, or a U.S. Merchant Mariner Document when on official business.
U.S. citizens entering the U.S. at sea or land ports of entry are required to have documents that comply with the Western Hemisphere Travel Initiative, which are a U.S. passport, a passport card, a trusted traveler card such as NEXUS, SENTRI, or FAST, or an enhanced driver’s license.