Turkey's decision to purchase Russian S-400 air defense system has become a major sticking point with the U.S. While Turkey attaches great importance to procuring the air defense system, U.S. policymakers, who consider Turkey's decision a complete deviation from its traditional alliance system, have begun to threaten the country.
While many focus nowadays on the S-400/F-35 tensions taking place in Turkish-American relations, another issue, namely Syria, is being discussed at the highest levels among officials from the two countries. For the last eight years, the divergence of policies in regards to the crisis in Syria has become one of the most significant irritants in bilateral relations.
New developments fuel tensions between Washington and Ankara. Despite U.S. President Donald Trump's promises to President Recep Tayyip Erdoğan over the phone, no problem has yet gone away. Quite the contrary, the foreign policy establishment and Congress continue to try and undermine bilateral relations.