US to arm Syrian Kurds fighting ISIS despite Turkish opposition Trump made the decision this week.

 -- President Trump has authorized the U.S. military to arm Syrian Kurdish rebel forces to support the future offensive on Raqqa, the de facto capital in Syria for ISIS. The move has been long opposed by Turkey which sees the groups as an extension of Kurdish terrorist organizations that have conducted attacks inside Turkey.

"Yesterday, the president authorized the Department of Defense to equip Kurdish elements of the Syrian Democratic Forces as necessary to ensure a clear victory over ISIS in Raqqa, Syria," Dana White, the Pentagon's chief spokesperson, said in a statement.

"The SDF, partnered with enabling support from U.S. and coalition forces, are the only force on the ground that can successfully seize Raqqa in the near future," said White.

The Syrian Democratic Forces is an umbrella organization of 40,000 fighters that includes both Syrian Kurdish and Arab rebel groups fighting ISIS in Syria. The main Kurdish element is the Kurdish Protection Units, known as the YPG, that has successfully pushed back ISIS from towns and cities in northern Syria.

There has been wide support from senior U.S. military officials to provide direct arms to Syrian Kurdish forces, but sensitivities about Turkish opposition has delayed such a decision.

The Turkish government considers the YPG to be an extension of the Kurdistan Workers Party, known by the acronym PKK, that has conducted terrorist attacks inside Turkey. But the U.S. sees the Kurdish group as its most reliable partner in the fight against ISIS in Syria.

"We are keenly aware of the security concerns of our coalition partner Turkey," said White in the statement. "We want to reassure the people and government of Turkey that the U.S. is committed to preventing additional security risks and protecting our NATO ally."

Last year the Obama administration authorized the supply of small arms, ammunition and vehicles to Arab forces aligned with the SDF. However, consideration of Turkey's opposition to arm the Kurdish forces delayed a decision by the Obama administration.

In January, the Obama administration's national security team recommended arming the SDF but President Obama decided it was better to let the incoming Trump administration decide on the matter.

President Trump approved the decision on Monday.

According to a U.S. official, the Syrian Kurdish forces will be provided with equipment and material similar to that provided to the Syrian Arab forces. The arms, ammunition and vehicles will be delivered in an incremental fashion.

"The U.S. continues to prioritize our support for Arab elements of the SDF," said White. "Raqqa and all liberated territory should return to the governance of local Syrian Arabs."

Traveling in Europe, Defense Secretary Jim Mattis spoke by phone with Turkish Defense Minister Fikri Isik about the administration's decision.

"Equipment provided to the SDF will be limited, mission specific, and metered out incrementally as objectives are reached," said White in a statement confirming the call. "The United States fully supports returning Raqqa to the care and governance of local Arabs. We do not envision a long-term YPG presence and governance in the city is acceptable or consistent with the wishes of the local population."

The city of Raqqa is being encircled by SDF forces who are receiving support from coalition airstrikes and American advisers. It is expected that the majority of the forces retaking the city will be Syrian Arab forces.

It remains unclear what potential impact this decision may have on plans for Turkish-supported rebel groups to participate in a future offensive on Raqqa.