There has been wide support from senior USA military officials to provide direct arms to Syrian Kurdish forces, but sensitivities about Turkish opposition has delayed such a decision.
President Donald Trump has authorized arming Kurdish fighters in Syria "as necessary to ensure a clear victory" in a planned assault to retake the city of Raqqa from Islamic State, the Pentagon said on Tuesday, in a likely blow to USA ties with Turkey.
The Pentagon statement said they are "the only force on the ground that can successfully seize Raqqa in the near future".
The issue is guaranteed to be front and center during a scheduled visit by Turkish President Recep Tayyip Erdogan to Washington next week.
"The U.S. continues to prioritize support for Arab elements of the SDF", he said.
In a sign of recent tensions, Turkish warplanes carried out air strikes against Kurdish YPG fighters in northeastern Syria and Iraq's Sinjar region late last month, killing less than 30 fighters, according to one estimate.
That partnership has generated friction with Ankara, which sees the YPG as an extension of the banned Kurdistan Workers' Party, or PKK, which is considered a terrorist group by both Turkey and the United States.
Just days after the Turkish defense minister's visit to Washington, almost two-dozen Turkish jets bombed three areas in northeast Syria and Iraq, killing roughly 20 members of the Syrian Kurdish fighters of the YPG.
Once the order comes to the Pentagon, the US can begin providing the Syrian Kurds with arms and equipment fairly quickly since some equipment is pre-positioned.
Tillerson said. "Once the ISIS threat has been reduced or eliminated, I think we can turn our attention directly to stabilizing the situation in Syria".
His approval gives the Pentagon the go-ahead to "equip Kurdish elements of the Syrian Democratic Forces as necessary to ensure a clear victory over ISIS" in Raqqa, said White, who was traveling with Defense Secretary Jim Mattis in Europe.
"The YPG is an arm of the PKK". She said Mattis spoke with his Turkish counterpart, Fikri Isik, by telephone to reiterate a US commitment to "protecting our North Atlantic Treaty Organisation ally".
"But we will work it out".
According to a USA official, the Syrian Kurdish forces will be provided with equipment and material similar to that provided to the Syrian Arab forces.
Noting that the USA continues to prioritise its support for Arab elements of the SDF, White said Raqqa and all the liberated territory should return to the governance of local Syrian Arabs.
"We're going to sort it out", Mattis said.
Speaking to Al Jazeera last month, Erdogan criticised Trump's predecessor, Barack Obama, over an agreement between the two to fight what he described as "terrorist groups" operating in Turkey.