Britain's Prime Minister Theresa May stressed on Wednesday that the British relationship with the European Union (EU) would change with Brexit."Our relationship with the EU will change with Brexit. But we will still be neighbours, we will still be part of the European family of nations, and we will continue to champion the same beliefs - standing for freedom, democracy and the rule of law, underpinned by a rules-based global order," she said.May's statement made during her speech at the 73rd session of the United Nations General Assembly."And my message today is that a post-Brexit Britain will be an unequivocally pro-business Britain - and a global partner that will help to lead the international response to those challenges," she noted.On Iran, May renewed her continued support for the international nuclear deal with Tehran."Ensuring non-proliferation also requires collective leadership, of the type that led to the agreement in 2015 of the Joint Comprehensive Plan of Action - the Iran nuclear deal," she pointed out."For many years, the scale and nature of Iran's nuclear programme raised serious international concerns. The JCPOA was an important step forward in addressing these," she stated.She noted that the deal "remains the best means of preventing Iran developing a nuclear weapon, and we are committed to preserving the JCPOA as long as Iran continues to abide by its obligations in full." "Iran must ensure they implement their obligations fully. And to monitor Iran's compliance, we strongly support the IAEA using inspections and other monitoring provisions of the JCPOA to their full." On Syria, she said "nowhere are the grim consequences of the erosion of global norms on Weapons of mass destruction more apparent than in Syria, where the UN has concluded that Asad's regime has repeatedly used chemical weapons, a direct assault on a near-century old ban vital to our collective peace and security." "Yet Russia has repeatedly wielded its veto to prevent the Security Council from holding the Asad regime to account, even shutting down the international body established to investigate chemical weapons use in Syria." She thanked US President Donald Trump and his French counterpart Emmanuel Macron for their determination to carry out a joint military attack last April on some sites of chemical weapons run by the Syrian regime.The Syrian regime's supporters should use their influence to guarantee that chemical weapons will not be used again, she said.She, however, warned that if these weapons are used again, Britain would respond quickly and in a proper way.