The presidents of the United States and Ukraine have signed an agreement laying out Washington’s long-term security relationship with Kiev. US President Joe Biden and Ukrainian President Ukrainian President Volodymyr Zelensky signed the bilateral deal on the sidelines of the G7 in southern Italy on Thursday. Fifteen countries have already concluded similar long-term security agreements with Ukraine, including Britain, France and Germany. Biden’s National Security Adviser Jake Sullivan said on Wednesday that the agreement would not include the obligation for Washington to deploy US troops to Uk…