You’re actually both right! Hyundais are made in the US, China, South Korea, and Pakistan for the various markets where they’re sold.
Sonatas meant for North American markets have been assembled in Montgomery, Alabama since 2005. Korea and China assemble the Sonata for Asian markets, while Pakistan rounds out the international assembly team by making Sonatas for their local market.
You can identify where your Hyundai Sonata was assembled by looking at the first few digits of your vehicle identification number (VIN). VINs beginning with the numbers 1, 4, and 5 were manufactured in the United States.