ANKARA (Reuters) - Turkey is ready to discuss U.S. concerns about the technical compatibility of Russian S-400 defences and U.S.-made F-35 jets, Defense Minister Hulusi Akar said Thursday, repeating Ankara’s proposal for a joint working group with Washington on the issue. U.S. President-elect Joe Biden is expected to be tougher on Turkey than was Donald Trump, particularly over its foreign and defence policies, and domestic human rights record. Biden could back U.S. congressional efforts to sanction Ankara over its purchase of the Russian S-400s missiles.