Whenever the President determines and reports to Congress in accordance with section 3173 of this title that a stay of sanctions or related actions pursuant to section 3171 of this title has not afforded sufficient time to obviate the risk to an ongoing criminal investigation or to an intelligence source or method that gave rise to the stay, he may extend such stay for a period of time specified by the President, which period may not exceed 120 days. The authority of this section may be used to extend the period of a stay pursuant to section 3171 of this title for successive periods of not more than 120 days each.