; (ii) any agency or instrumentality of the armed forces of Iran; (iii) any agency or instrumentality related to the nuclear program of Iran; or (iv) any organization designated as a foreign terrorist organization under section 219 of the Immigration and Nationality Act ( 8 U.S.C. 1189 ), including Hamas, Hezbollah, Palestinian Islamic Jihad, alQa’ida, and al-Shabaab. 4. Restrictions on certain financial institutions (a) In general Not later than the date that is 90 days after submitting a report described under section 3(a)(1), the Secretary shall undertake the following with respect to a financial institution that is described under section 3(a)(1)(C) and listed in the report: (1) If the financial institution is a United States financial institution, require the closure of any account described in section 3(a)(1)(C)(i), and prohibit the provision of significant financial services, directly or indirectly, to a natural person covered by the report. (2) If the financial institution is a foreign financial institution, actively seek the closure of any account described in section 3(a)(1)(C)(i), and the cessation of significant financial services to a natural person covered by the report, using any existing authorities of the Secretary, as appropriate. (b) Suspension The Secretary may suspend the application of subsection (a) with respect to a financial institution upon reporting to the appropriate Members of Congress that the suspension is in the national interest of the United States, with a detailed explanation of the reasons therefor. 5. Exceptions for national security