SINGAPORE (Reuters) -A rebound in the dollar (DX=F) proved short-lived on Tuesday following renewed signs of strains in U.S.-China trade relations, which dented risk sentiment and left investors ducking for cover in traditional safe havens like the yen and the Swiss franc. Just as markets found some reprieve after U.S. President Donald Trump struck a more conciliatory tone against tariffs on China, and on signs that a meeting with his Chinese counterpart was on track for later this month, developments on ...