For each fiscal year, Congress shall authorize the strength for active duty personnel of the Coast Guard as of the end of that fiscal year. Amounts may be appropriated for a fiscal year to or for the use of active duty personnel of the Coast Guard only if the end strength for active duty personnel for that fiscal year has been authorized by law. If at the end of any fiscal year there is in effect a declaration of war or national emergency, the President may defer the effectiveness of any end-strength limitation with respect to that fiscal year prescribed by law for any military or civilian component of the Coast Guard, for a period not to exceed 6 months after the end of the war or termination of the national emergency.