ISTANBUL • Washington's latest plan to aid Syrian fighters battling the Islamic State in Iraq and Syria (ISIS) has hit a bump - Turkish officials summoned the US ambassador to express concern that America was providing new support to Kurdish militants in Syria seen by Turkey as a primary enemy.
In a twist, Turkey also summoned the Russian ambassador over concerns that Moscow, too, was helping the Kurds. Another point of contention could be unfolding, as the two sides compete for Kurdish affections.
That would further complicate the tangled battle lines inside Syria and could upend the US relationship with Kurdish militias - America's most important on-the-ground partner inside Syria in the fight against ISIS.
The Turks' decision to summon the US envoy on Tuesday was partly a reaction to a move by the US to airdrop 50 tonnes of ammunition over the weekend to members of an Arab-Kurdish coalition. The US wants to build up this coalition so it can take on ISIS at the group's stronghold in Raqqa.
US officials say that the equipment is meant only for Arab fighters in the coalition. However, multiple fighters on the ground say that, in practice, they operate under Kurdish auspices.
Turkey is generally concerned about the growing US partnership with Syrian Kurdish militias, which Ankara links to Kurdish fighters inside the country who have long fought the Turkish state.
Perhaps more significant in the long run is the potential competition between Russia and the US for the allegiance of the Syrian Kurds.
The US has long backed the Syrian Kurdish militia known as the People's Protection Units, or YPG, going back to the battle last year for the city of Kobane. Now, it appears that Russia might be cosying up to the group too.
Reports have emerged in recent days that Russian officials have met Mr Salih Muslim, the leader of the Democratic Union Party, whose armed wing is the YPG.
Russia has historical ties to the group dating back to Soviet days. The YPG is the Syrian offshoot of the Kurdistan Workers' Party, or PKK, which began waging an insurgency against Turkey in the 1980s - a conflict that was recently resumed after failed peace talks.
"Turkey will not accept any cooperation with terror groups fighting against Turkey," Dr Ahmet Davutoglu, the country's Prime Minister, said at a news conference on Wednesday in Istanbul.
"We have shared this with the US and Russia."
NEW YORK TIMES