Obama defeated Republican opponent Mitt Romney and his running mate Paul Ryan in the 2012 presidential election. In his second term, Obama advocated for gun control in the wake of the Sandy Hook Elementary School shooting, took steps to combat climate change, signing the Paris Agreement, a major international climate agreement, and an executive order to limit carbon emissions. Obama also presided over the implementation of the Affordable Care Act and other legislation passed in his first term. He initiated sanctions against Russia following the invasion in Ukraine and again after Russian interference in the 2016 U.S. elections, ordered military intervention in Iraq in response to gains made by ISIL following the 2011 withdrawal from Iraq, negotiated the Joint Comprehensive Plan of Action (a nuclear agreement with Iran), and normalized relations with Cuba. The number of American soldiers in Afghanistan decreased during Obama's second term, though U.S. soldiers remained in the country throughout the remainder of his presidency. Obama promoted inclusion for LGBT Americans, becoming the first sitting U.S. president to publicly support same-sex marriage.