Ten of Myanmar's major rebel groups threw their support behind the country's anti-coup movement Saturday, fanning fears that a broader conflict could erupt in a country long plagued by fighting between the military and the ethnic armies. Myanmar has been in turmoil since the military ousted civilian leader Aung San Suu Kyi on February 1, triggering an uprising that the junta has sought to quell with deadly crackdowns. According to a local...