part of customary international law. Countries implementing exit visas vary in who they require to obtain one. Some countries permit the free movement of foreign nationals while restricting their own citizens. Others may limit the exit visa requirement to resident foreigners in the country on work visas, such as in the Kafala system. Asia Iraq, Kuwait, Lebanon, Oman, Saudi Arabia, and the United Arab Emirates all have an exit visa requirement for alien foreign workers. This is part of their kafala work visa sponsorship system. Consequently, at the end of a foreign worker's employment period, the worker must secure clearance from their employer stating that the worker has satisfactorily fulfilled the terms of their employment contract or that the worker's services are no longer needed. The exit visa can also be withheld if there are pending court charges that need to be settled or penalties that have to be meted out. In September 2018, Qatar lifted the exit visa requirement for most workers. Persons are generally free to leave Israel, except for those who are subject to a stay of exit order. Nepal requires its citizens emigrating to the United States on an H-1B visa to present an exit permit issued by the Nepali Ministry of Labour. This document is called a work permit and needs to be presented to Nepali immigration to leave Nepal. Uzbekistan was the last remaining country of the former USSR that required an exit visa, which was valid for a two-year period. The practice was abolished in 2019. There had been explicit United Nations complaint about this practice. North Korea requires that its citizens obtain an exit visa stating the traveller's destination country and time to be spent abroad before leaving the country. Additionally, North Korean authorities also require North Korean citizens to obtain a re-entry visa from a North Korean embassy or North Korean mission abroad before being allowed back into North Korea. The government of the People's Republic of China requires its citizens to obtain a two-way permit (visiting), or one-way permit (emigrating) issued by the People's Republic of China's authorities, prior to visiting Hong Kong or Macau. The two-way permit and one-way permit are a de facto exit visa for Hong Kong- or Macau-bound trips for citizens of the People's Republic of China. Singapore operates an Exit Permit scheme in order to enforce the national service obligations of its male citizens and