EU's third biggest trading partner after the United States and China. Some member states, notably Belgium, Cyprus, Ireland, Germany and the Netherlands, are more exposed to a Brexit-induced economic shock. The economy of the Republic of Ireland is particularly sensitive due to its common land border with the United Kingdom and its close agribusiness integration with Northern Ireland. The reintroduction of a customs border would have been economically and politically damaging to both sides, particularly because of the risk to the Northern Ireland peace process that a physical border presents. Despite protestations of good will on both sides, it was not obvious how border controls could have been avoided unless the UK has a Customs Union with the EU. Arising from the agreements made at the Phase 1 negotiations (after the DUP intervention), any arrangements to be made to facilitate cross-border trade in Ireland will apply equally to cross-Channel trade but the details remain unclear. In October 2019, the UK and EU renegotiated the Northern Ireland Protocol of the draft Brexit Withdrawal Agreement so as to keep open the border in Ireland and to have a customs border between the island of Ireland and the island of Great Britain (leaving Northern Ireland 'de facto' in the EU Customs Union in some respects). The sectors across the EU that would be most hit by the UK's withdrawal are motor vehicles and parts (the UK is a large manufacturer and depends on an EU chain of supply for parts), electronics equipment and processed foods. Export of raw materials from the Ruhr valley would also be impacted. Internal trade Ferry companies DFDS and CLdN have announced plans for new or additional direct services from Ireland to the mainland, avoiding anticipated delays and disruption on the traditional route via Great Britain. Fisheries In May 2021, France threatened to cut off electricity to the British Channel Island of Jersey in a fight over post-Brexit fishing rights. People EU migration or Freedom of movement The impact of this would be felt most on eastern European member states who have approximately 1.2 million workers in the UK by the end of 2015; the largest groups from Poland (853,000), Romania (175,000) and Lithuania (155,000). A year after the Brexit vote, net annual immigration to the UK fell by 106,000 with most attributed to EU citizens leaving for other states, with the biggest drop among those from the western