citizens of each country to reside and work in the other country, with some restrictions. Other details of the arrangement have varied over time. From 1 July 1981, all people entering Australia (including New Zealand citizens) have been required to carry a passport. Since 1 September 1994 Australia, has had a universal visa requirement, and to specifically cater for the continued free movement of New Zealanders to Australia, the Special Category Visa was introduced for New Zealanders. Central America :The Central America-4 Border Control Agreement abolishes border controls for land travel between El Salvador, Honduras, Nicaragua, and Guatemala. However, this does not apply to air travel. Europe and the Middle East Union State of Russia and Belarus The Union State of Russia and Belarus is a supranational union of Russia and Belarus, which eliminates all border controls between the two nations. Before a visa agreement was signed in 2020, each country maintained its own visa policies, thus resulting in non-citizens of the two countries generally being barred from travelling directly between the two. However, since the visa agreement was signed, each side recognises the other's visas, which means that third-country citizens can enter both countries with a visa from either country. Western Europe: The two most significant free travel areas in Western Europe are the Schengen Area, in which very little if any border control is generally visible, and the Common Travel Area (CTA), which partially eliminates such controls for nationals of the United Kingdom and Ireland. Between countries in the Schengen Area, and to an extent within the CTA on the British Isles, internal border control is often virtually unnoticeable, and often only performed by means of random car or train searches in the hinterland, while controls at borders with non-member states may be rather strict. Gulf Cooperation Council: Members of the Gulf Cooperation Council, or GCC, allow each other's citizens freedom of movement in an arrangement similar to the CTA and to that between India and Nepal. Between 5 June 2017 and 5 January 2021, freedom of movement in Saudi Arabia, the UAE, and Bahrain was suspended for Qataris as a result of the Saudi-led blockade of the country. Hostile environment policies Certain jurisdictions gear their immigration policies toward creating a hostile environment for undocumented migrants in order to deter migration by creating an unwelcoming atmosphere for potential and existing immigrants. Notably, the British Home Office adopted a