The diplomatic tensions between Turkey and the United States continue to escalate. On Sunday, the United States suspended non-immigrant visas for Turkish citizens. On Monday, Turkey retaliated by suspending non-immigrant visas for American citizens. This effectively bans tourist travel for citizens between the two countries. The reason for the increased tensions is the recent arrest of a US Consulate official, who is suspected of having ties to the Gülen movement.
Bottom Line
If you are only connecting in Istanbul, then this issue won't apply to you. Hopefully this diplomatic row will be resolved in a timely manner. If you are flying to Turkey in the next few weeks, I'd contact your airline to determine how to best move forward. Turkish Airlines is currently offering refunds for flights from October 9th – 31st.