Reducing Crime and Terrorism at America's Seaport Act of 2003

Reducing Crime and Terrorism at America's Seaports Act of 2003 - Amends the Federal criminal code to prohibit: (1) entry by false pretenses to a secure area of a seaport; (2) knowingly failing to obey an order to heave to by an authorized Federal officer; (3) forcibly interfering with an authorized law enforcement action or providing false information during a boarding; (4) willfully disabling a passenger vehicle; and (5) unlawfully and intentionally destroying any aid to maritime navigation maintained by the Saint Lawrence Seaway Development Corporation that endangers safe navigation.

Sets penalties for knowingly and intentionally: (1) placing in U.S. waters a device or substance likely to destroy or damage a vessel or its cargo or likely to interfere with safe navigation or maritime commerce; (2) discharging or releasing into U.S. navigable water or adjoining shoreline any substance that would endanger human life, health, or welfare or the marine environment; (3) transporting aboard any vessel explosive, biological, chemical, or radioactive or nuclear material to be used to commit a Federal crime of terrorism.

Sets penalties for: (1) transporting aboard any vessel a terrorist or terror suspect; (2) willfully causing destruction of a vessel or maritime facility; (3) imparting or conveying false information concerning an attempt made to commit certain criminal acts; and (4) knowingly carrying a weapon, explosive, incendiary device, or loaded firearm on a vessel or at a seaport.

Requires the Attorney General to issue regulations to require the reporting of cargo theft.

Expands the scope of a prohibition against theft of interstate or foreign shipments.

Amends the Tariff Act of 1930 to increase penalties for noncompliance with manifest requirements.