BISHKEK: A decision by US President Barack Obama to send special forces to Syria is strictly focused on fighting Islamic State insurgents and does not signify the United States is entering the civil war there, US Secretary of State John Kerry said.

"President Obama has made a very strong and forceful and simple decision entirely in keeping with his originally stated policy that we must defeat and destroy Daesh," Kerry said, using the Arabic term for Islamic State.

"It is not a decision to enter into Syria's civil war. It is not an action focused on (Syrian President Bashar) Assad, it focused exclusively on Daesh and in augmenting our ability to rapidly attack Daesh," Kerry told a news briefing during a visit to Kyrgyzstan's capital, Bishkek.

Asked about the prospect of the United States sending more troops, or getting drawn deeper into the conflict, Kerry said: "I can’t predict what the future will bring when our policy is to destroy Daesh, to fight back against this evil. But I do think the president has made a judgment that I completely advocated for and concur (with)."

The White House announced on Friday that dozens of special operations troops will be deployed to northern Syria to advise opposition forces in their fight against Islamic State, which is also known by the acronym ISIL.

The decision marked a policy shift for Obama, who has long resisted sending troops to avoid getting sucked into another war in the Middle East.

Kerry, at the start of a tour of the five ex-Soviet republics in Central Asia, described Islamic State, as "a destroyer and it is threatening to take actions against America, Canada and Mexico, against countries all around the world. So ISIL is a... threat that we have to respond to."

Kerry is in the region in part to reassure governments that are anxious about the threat from Islamist militants, especially those operating in nearby Afghanistan, according to a US official who briefed reporters on the trip.

Kyrgyzstan's acting foreign minister, Erlan Abdyldayev, said at the news briefing with Kerry that his government was concerned about instability in northern Afghanistan.

He said the subject would be discussed when, later in his tour, Kerry meets foreign ministers from the five central Asian states in the Uzbek city of Samarkand.