This bill, known as the "Seaport Security Act of 2026," aims to safeguard United States seaports from the growing threat posed by unmanned aircraft systems (UAS), or drones. Congress finds that while drone technology has revolutionary potential, it also presents significant dangers, including its use for criminal activities like trafficking and reconnaissance. Given that U.S. seaports are critical infrastructure, a drone attack could severely compromise national and economic security, a vulnerability not adequately addressed by current federal law. The Act amends title 18 of the U.S. Code to prohibit the operation of unauthorized unmanned aircraft within covered airspace over seaports, defined as up to 1,000 feet above ground level and potentially additional areas designated by the Federal Aviation Administration (FAA) Administrator. A "seaport" is specifically defined as facilities handling at least one million tons of commercial or military cargo annually or routinely processing multi-day cruise passengers. Exceptions to this prohibition include operations by Federal agencies, State or local law enforcement with prior notification, and seaport-contracted entities for operational or security purposes, as well as FAA-authorized waivers or emergency responses. Beyond airspace restrictions, the bill also prohibits any drone operation that interferes with a seaport's security, operations, communications, or navigational systems, regardless of altitude. To ensure compliance, the FAA and seaports are empowered to detect, mitigate, seize, and disable unauthorized unmanned aircraft. Violators face substantial civil penalties of up to $25,000 per violation and potential aircraft seizure, while willful violations carry criminal penalties of up to 2 years imprisonment, or up to 10 years if committed with intent to surveil, damage, disrupt, or facilitate criminal or terrorist activity. The FAA is mandated to issue comprehensive regulations to implement these provisions within 180 days.