WASHINGTON—The Biden administration has extended for one year a Trump-era ban on the use of U.S. passports for travel to North Korea. The ban had first been imposed by former Secretary of State Rex Tillerson in 2017 after the death of American student Otto Warmbier, who suffered grievous injuries while in North Korean custody. It has been extended annually ever since. The State Department announced the extension of the ban until Aug. 31, 2022, in a Federal Register notice to be published on Thursday. Humanitarian groups have expressed concern about the impact the initial ban and its extensions have had on providing relief to isolated North Korea, which is one of the world’s neediest countries. The ban makes it illegal to use a U.S. passport for travel to, from, or through North Korea, also known as the Democratic People’s Republic of Korea, or the DPRK, unless the document has been …