The United States has issued regulations to enact the provisions of the Maritime Transportation Security Act of 2002 and to align domestic regulations with the maritime security standards of SOLAS and the ISPS-Code. These regulations are found in Title 33 of the Code of Federal Regulations, Parts 101 through 107. Part 104 contains vessel security regulations, including some provisions that apply to foreign ships in U.S. waters.
Europe has enacted the International regulations with EC-Regulation No_725/2004 of the European Parliament and of the Council of March 31, 2004, on enhancing ship and port facility security and the EC-Directive 2005/65 of the European Parliament and of the Council of October 26, 2005 on enhancing the safety of ports.
Some countries have not signed the SOLAS convention. Ships from these countries can therefore not be treated as secure ships. You can find the list of countries here.