 Complete the following phrase:  During the 2010s, the country has seen troubles in race relations. After the killings of many African Americans such as Eric Garner, Michael Brown, and Philando Castile by policemen resulted in no prosecution, the Black Lives Matter movement sparked discussions, protests, and riots against racial profiling, police brutality, and overall racism between white and black Americans. America saw the rise of the alt-right movement. In August 2017, these groups attended a rally in Charlottesville, Virginia, during which a neo-Nazi rammed a car into and killed a protester against the rally. Since the mid-2010s, the Department of Homeland Security and the Federal Bureau of Investigation now consider the threat of white supremacist and alt-right violence the leading threat of domestic terrorism in the United States. A series of deadly mass shootings, especially the Aurora movie theater massacre and the Sandy Hook Elementary School massacre, sparked a heated debate over gun control and the causes of these events. The 