The United States has issued a warning to its citizens of "credible threats" of extremist attacks in tourist areas of Turkey.
The U.S. Embassy in Turkey on April 9 warned American citizens to exercise extreme caution, particularly in Istanbul and the southern coastal resort of Antalya.
Turkey is facing multiple security threats.
As part of a U.S.-led coalition, Ankara is fighting Islamic State in neighboring Syria and Iraq. It is also battling Kurdish militants in Turkey's southeast, where a ceasefire collapsed last July, triggering the worst violence since the 1990s.
Turkey has been hit by four suicide bombings already this year, the most recent one last month in Istanbul. Two of those have been blamed on Islamic State, while Kurdish militants have claimed responsibility for the other two.