The Obama administration made public its case that Syrian President Bashar al-Assad was responsible for a chemical-weapons attack outside Damascus, bracing Americans for potential strikes in the coming days. President Barack Obama said he hasn't made a decision on military strikes on Syria, even as U.S. forces continued a buildup in the Middle East on Friday and the White House took the rare step of releasing a detailed U.S. intelligence assessment. The U.S. findings, based on intercepted communications, satellite images and human spying, were released to underpin Mr. Obama's assertions that the Assad regime was responsible for the attack, which...