Turkish President Tayyip Erdogan has said he will discuss buying U.S. Patriot missiles with President Donald Trump this month, saying his personal bond with the U.S. Leader could overcome a crisis caused by Ankara buying Russian air defence systems.

Turkey’s purchase of the Russian S-400 missile system in July raised the prospect of U.S. Sanctions, and the state department has said an offer to sell Raytheon Co’s patriot missile defence system to Ankara has expired.

President Erdogan told Reuters he had discussed buying patriots in a phone call with Trump two weeks ago and would follow up when they meet at the U.N. General Assembly, which opens next week.