((a)) ** In general** The President shall—
((1)) within 6 months after receipt of a report by the Secretary under subsection (a), (d)(1), or (f) of , withdraw the assignment to a Federal Government station of any frequency which the report recommends for immediate reallocation;
((2)) within any such 6-month period, limit the assignment to a Federal Government station of any frequency which the report recommends be made immediately available for mixed use under ;
((3)) by the delayed effective date recommended by the Secretary under (except as provided in subsection (b)(4) of this section), withdraw or limit the assignment to a Federal Government station of any frequency which the report recommends be reallocated or made available for mixed use on such delayed effective date;
((4)) assign or reassign other frequencies to Federal Government stations as necessary to adjust to such withdrawal or limitation of assignments; and
((5)) transmit a notice and description to the Commission and each House of Congress of the actions taken under this subsection.
((b)) ** Exceptions**
((1)) ** Authority to substitute** If the President determines that a circumstance described in paragraph (2) exists, the President—
((A)) may substitute an alternative frequency or frequencies for the frequency that is subject to such determination and withdraw (or limit) the assignment of that alternative frequency in the manner required by subsection (a); and
((B)) shall submit a statement of the reasons for taking the action described in subparagraph (A) to the Commission, Committee on Energy and Commerce of the House of Representatives, and the Committee on Commerce, Science, and Transportation of the Senate.
((2)) ** Grounds for substitution** For purposes of paragraph (1), the following circumstances are described in this paragraph:
((A)) the reassignment would seriously jeopardize the national defense interests of the United States;
((B)) the frequency proposed for reassignment is uniquely suited to meeting important governmental needs;
((C)) the reassignment would seriously jeopardize public health or safety;
((D)) the reassignment will result in costs to the Federal Government that are excessive in relation to the benefits that may be obtained from commercial or other non-Federal uses of the reassigned frequency; or
((E)) the reassignment will disrupt the existing use of a Federal Government band of frequencies by amateur radio licensees.
((3)) ** Criteria for substituted frequencies** For purposes of paragraph (1), a frequency may not be substituted for a frequency identified and recommended by the report of the Secretary under unless the substituted frequency also meets each of the criteria specified by .section 923(a) of this titlesection 923(a) of this title
((4)) ** Delays in implementation** If the President determines that any action cannot be completed by the delayed effective date recommended by the Secretary pursuant to , or that such an action by such date would result in a frequency being unused as a consequence of the Commission’s plan under , the President may—
((A)) withdraw or limit the assignment to Federal Government stations on a later date that is consistent with such plan, except that the President shall notify each committee specified in paragraph (1)(B) and the Commission of the reason that withdrawal or limitation at a later date is required; or
((B)) substitute alternative frequencies pursuant to the provisions of this subsection.