; and (6) identifies gaps in BTTF technological capability to detect cross-border tunnel threats. . (b) Clerical amendment The table of contents in section 1(b) of the Homeland Security Act of 2002 is amended by inserting after the item relating to section 420B, as added by this title, the following new item: Sec. 420C. Border Tunnel Task Forces. . 434. Subterranean operations (a) In general Subtitle B of title IV of the Homeland Security Act of 2002 ( 6 U.S.C. 211 et seq.), as amended by this title, is further amended by adding at the end the following new section: 420D. National Subterranean Operations Program (a) Establishment There is established within U.S. Customs and Border Protection a program to known as the National Subterranean Operations Program (referred to in this section as the program ). The program shall be headed by an Assistant Chief, who shall be appointed by the Chief of the U.S. Border Patrol. (b) Purpose The purpose of the program is the following: (1) To apply risk-based criteria to interdict and remediate illicit cross-border tunnels identified by technology, intelligence leads, agency partners, and relevant Federal entities as determined by the Assistant Chief. (2) To patrol and secure underground municipal infrastructure. (c) Authorization of appropriations There is authorized to be appropriated $4,000,000 for each of fiscal years 2021 and 2022 to carry out this section. . (b) Counter tunnel operations strategic plan (1) In general Not later than 180 days after the date of the enactment of this Act, the Assistant Chief of the National Subterranean Operations Program of U.S. Customs and Border Protection (established pursuant to section 420 of the Homeland Security Act of 2002 (as added by subsection (a))) shall establish the following: (A) Risk-based criteria to be used to prioritize the interdiction and remediation of illicit cross-border tunnels identified by technology, intelligence leads, agency partners, and other relevant Federal entities as determined by the Assistant Chief. (B)