Gen. Joseph Dunford, Chairman of the US Chiefs of Staff, Gen. Valery Gerasimov, Russian Chief of Staff, and Gen. Hulusi Akar, Turkish army chief, were conferring in Antalya when the Rangers landed in Syria.
The last Erdogan-Putin meeting was held last August after Turkey and Russia patched up the fallout from the November 2015 downing of a Russian jet over the Turkey-Syria border. It comes amid renewed Turkish threats to hit USA -backed Syrian Kurdish targets in the northern Syrian city of Manbij.
The U.S. has a few hundred special operations forces embedded with the Syria Democratic Forces and wants the alliance to lead the march on Raqqa.
". It appears that the US may carry out this operation with the YPG, not with Turkey".
The U.S. and Russian moves leave Turkey with "no more room to maneuver", said Faysal Itani, an analyst with the Atlantic Council in Washington.
Turkey is cooperating with Russian Federation in Syria, despite them being at odds politically over the future of Syrian President Bashar al-Assad, whom Moscow backs militarily.
Turkey, however, has labeled Kurdish militants such as those belonging to the People's Protection Units within the SDF as terrorists and has refused to recognize their position in the larger fight against ISIS.
"It is a measure of the success that forces are having in countering the Islamic State of Iraq and Syria that the conversation is necessary", the U.S. Defense Department said in a statement.
Last week Russian fighters launched airstrikes against a USA camp in Syria, which had been training anti-Assad Syrian militiamen battling Islamic State.
It came after Russian and Syrian regime forces started to move "humanitarian" convoys into Manbij, making it more hard for Turkish troops to launch the offensive they had threatened.
Binali Yildirim, Turkey's prime minister, said the meeting would continue on Wednesday. Right next to them are pro-government Syrian regime forces. Before, the two officers had not met face-to-face since 2014, when the United States broke off most contact between the USA and Russian militaries after Moscow launched military operations in Ukraine and annexed that country's Crimean Peninsula as its own.
The Pentagon said Monday it had sent extra troops into northern Syria to make sure competing forces in and around Manbij remain focused on fighting IS rather than each other.