Turkey does not expect ties with the United States to be strained under President-elect Joe Biden and does not anticipate sanctions over its purchase of Russia S-400 defence systems, a senior official in President Tayyip Erdogan’s AK Party said. Relations have been tense between Ankara and Washington over issues from policy toward Syria to the U.S. refusal to extradite a cleric Turkey blames for a 2016 coup attempt. Turkey has relied on the good personal ties between Erdogan and U.S. President Donald Trump to smooth over divisions, but Biden is expected to be tougher on Turkey over foreign and defence policies and Ankara’s human rights record. Ankara’s purchase last year of the S-400s, which are not compatible with NATO defences, raised the prospect of U.S. sanctions early next year if Congress approves a defence spending bill which the House of Representatives has already voted to include language requiring the president to sanction Turkey.