LONDON – The first event of Defense Secretary Ash Carter’s four-day trip to Europe will focus on reaffirming the relationship between the United States and United Kingdom following this summer’s Brexit vote.

Carter is set to give a speech Wednesday at Oxford University, where as a Rhodes Scholar he worked toward his doctorate in theoretical physics. The secretary told reporters traveling with him to the United Kingdom that the speech will discuss the future of the security relationship between the U.S. and Great Britain, as well as the campaign against the Islamic State and efforts to counter Russian aggression.