ANKARA (Reuters) - Finding a diplomatic solution with the United States and Russia on northern Syria's Manbij has become a necessity, and a military approach would only be considered if diplomacy failed, Turkish Defense Minister Fikri Isik said on Thursday.

Speaking to broadcaster A Haber in an interview, Isik also said Turkey was considering every option to prevent Kurdish militants from taking a foothold in Iraq's Sinjar, including a joint ground operation with the forces of the Masoud Barzani, President of the Iraqi Kurdish Region.

The Syrian-Kurdish YPG militia, which Turkey considers a terrorist organization, is the dominant party in a U.S.-backed alliance currently controlling Manbij. It is unclear how large a presence the YPG has in Manbij.

(Reporting by Ece Toksabay and Tuvan Gumrukcu; Editing by David Dolan)