By Dan WilliamsJERUSALEM (Reuters) - Israeli Prime Minister Benjamin Netanyahu pledged to crack down on Monday against threatened no-shows for military reserve duty by opponents of his judicial overhaul plan, saying such actions were anti-democratic and risked emboldening the country's foes. Critics of the judicial overhaul plan say it is Netanyahu who is threatening democracy by removing checks and balances. A former air force officer heading a group of reservist pilots and navigators opposed to the judicial overhaul told Reuters none had yet refused call-ups. Should it happen, he said, "there would be a severe problem for the country" given about 50% of crews on air force combat missions are reservists. Netanyahu, on trial for corruption charges he denies, backs the changes as restoring balance between branches of government.