National Security Readiness Act of 2003

National Security Readiness Act of 2003 - Amends the Endangered Species Act of 1973 to prohibit the Secretary of the Interior (or the Secretary of Commerce, as appropriate) from designating as critical habitat any land or geographical area controlled by the Department of Defense, or designated for its use, that are subject to an integrated natural resources management plan for a military installation under the Sikes Act, if the Secretary determines that the plan addresses special management considerations or protections.Amends the Marine Mammal Protection Act of 1972 to: (1) redefine the term "harassment" as it relates to marine mammals; and (2) authorize the Secretary of Defense, after conferring with the Secretary of Commerce or the Secretary of the Interior, to exempt any action undertaken by the Department of Defense from requirements of the Act, if the Secretary of Defense determines that the action is necessary for national defense.Exempts the Secretary of the Interior (or, as appropriate, the Secretary of the department in which the National Oceanic and Atmospheric Administration is operating) from the requirement to publish notice (except in the Federal Register) with respect to incidental takings of marine mammals and marine mammal products while engaged in military readiness activities authorized by the Secretary of Defense. (Currently, the appropriate Secretary is required to publish notice also in newspapers of general circulation, and through electronic media, in the coastal areas that may be affected.)