Three informed sources told Reuters that the administration of U.S. President Joe Biden sent a letter to members of Congress on Wednesday, urging them to approve a $20 billion deal for F-16 fighter jets manufactured by Lockheed Martin and modernization tools for Turkey. The Turkish parliament approved Sweden's request to join NATO on Tuesday, removing a significant obstacle to expanding the Western military alliance after a 20-month delay. The sources said that the letter was sent on Wednesday, and that the administration has not yet officially informed Congress about the sale plans. Turkey's failure to ratify was a key hurdle in obtaining congressional approval for the fighter jet deal. Lawmakers stated that they were waiting for approval of Sweden's request, including President Recep Tayyip Erdoğan's signature, before deciding whether to agree to the sale. Leaders of the Senate Foreign Relations Committee and the House Foreign Affairs Committee review all major foreign arms sales. They regularly raise questions or concerns about human rights issues or diplomatic matters that could delay or halt such deals.