Trump declares public health emergency to end opioid scourge in U.S.

U.S. President Donald Trump signs a presidential memorandum during an event highlighting efforts to battle the opioid crisis at the White House in Washington D.C., the United States, on Oct. 26, 2017. Trump on Thursday declared the opioid crisis "a national public health emergency" in the United States and vowed to "build a wall" to confront the growing scourge. (Xinhua/Ting Shen)