The "Countering Beijing's Weaponization of Fentanyl Act" (S. 63) proposes significant amendments to the Chemical and Biological Weapons Control and Warfare Elimination Act of 1991. Its core purpose is to expand the existing law to impose sanctions on foreign countries whose governmental entities commit acts involving chemical or biological programs that cause injury or damages to other foreign nations. Crucially, the bill explicitly defines "chemical or biological program" to include the production, development, or distribution of chemical or biological weapons, as well as specific fentanyl precursors such as benzylfentanyl, 4-anilinopiperidine, and norfentanyl precursors. The legislation mandates that the President determine within 60 days if an official, employee, or agent of a foreign governmental entity has committed a "covered act." A covered act is defined as an action where the individual knew or should have known it would injure another foreign country, and it concerns a chemical or biological program owned, controlled, or directed by that entity. Upon such a determination, the President shall impose a series of sanctions on the foreign country most closely associated with the responsible entity. These sanctions are structured in a tiered approach, beginning with initial measures within 30 days of a determination. These include the suspension of scientific cooperative programs and a prohibition on the export of certain controlled items and procurement from the country's chemical or biological sectors. If the foreign entity or government fails to adequately address the act, provide substantive information, or develop prevention measures within 120 days, the President must impose at least two additional intermediate sanctions, such as terminating most foreign assistance or prohibiting further exports of controlled items. A final round of sanctions is mandated within 210 days if the issues persist, requiring the President to prohibit certain financial transactions involving the country's financial interests that are subject to U.S. jurisdiction. The President may waive the imposition of sanctions for national security reasons for periods of up to 180 days, although this waiver authority sunsets after five years. Sanctions can be terminated after one year if the country or entity adequately addresses the act, makes restitution, provides information, develops prevention measures, and complies with relevant treaties like the Biological and Chemical Weapons Conventions.