Otto Warmbier North Korea Nuclear Sanctions Act (Sec. 3) This bill directs the Department of the Treasury to prohibit a foreign financial institution that knowingly provides significant financial services to a "covered person" from opening or maintaining a correspondent account in the United States. "Covered person" includes any person doing business with North Korea, any North Korean person employed outside North Korea (unless waived by Treasury), and any person that knowingly employs a North Korean person outside North Korea. The bill establishes civil and criminal penalties for violations. Treasury must prohibit a U.S.-based financial institution from knowingly engaging in a significant transaction with a covered person. The bill establishes civil penalties for violations. (Sec. 4) The bill amends the Bretton Woods Agreements Act to direct the United States to oppose international financial assistance for a foreign government that does not implement these sanctions against North Korea. The President may waive this directive after specified steps are taken. The bill amends the Export-Import Bank Act to prohibit the bank from providing support to a covered person. (Sec. 5) Treasury must report on compliance with this bill among financial institutions, including any penalties imposed and efforts by Treasury to support compliance. The bill amends the International Financial Institutions Act to require Treasury to: (1) instruct the U.S. Executive Director at the International Monetary Fund (IMF) to support the use of the IMF's administrative budget for technical assistance that strengthens the capacity of IMF members to prevent money laundering and the financing of terrorism, and (2) report on the effectiveness of such assistance. (Sec. 6) The President may suspend or terminate sanctions under this bill if certain steps regarding nonproliferation of weapons of mass destruction are taken by North Korea.