WASHINGTON—President Donald Trump hosted Mexican President Andres Manuel Lopez Obrador at the White House for the first time to celebrate the launch of the new North American trade agreement known as USMCA. The two leaders met on July 8 to discuss the strategic cooperation between the two countries on both trade and immigration. “The relationship between the United States and Mexico has never been closer than it is right now,” Trump said at the Rose Garden before signing a joint declaration with his counterpart. The declaration aims to bolster economic and security cooperation. He noted that “people were betting against” a good relationship between the leaders. “Each of us was elected on the pledge to fight corruption, return power to the people, and put the interests of our countries first,” Trump said. The U.S.–Mexico–Canada Agreement (USMCA) took effect on July 1, opening a new chapter in North American free trade. Known as T-MEC in Mexico, USMCA has strong labor provisions and..