The "39 countries" refers to an expanded U.S. travel and immigration ban announced in December 2025 by the Trump administration, affecting nationals from countries deemed to have inadequate security vetting, including additions like Nigeria, Angola, and Venezuela, alongside original nations such as Afghanistan, Iran, and Syria, with some facing full bans (immigrant/nonimmigrant) and others partial restrictions (like visitor/student visas), affecting millions for travel and work, effective January 1, 2026.