BAGHDAD — President Barack Obama's envoy to the U.S.-led coalition against the Islamic State group visited northern Syria over the weekend, a coalition official said, marking the first known visit by a senior U.S. official to Syria since the beginning of the U.S.-led campaign against IS in August 2014.

Brett McGurk was joined by British and French officials in Kobani, where Kurdish forces aided by U.S.-led airstrikes drove back IS militants a year ago, handing the extremists one of their biggest defeats.

The official spoke to The Associated Press on condition of anonymity because he was not authorized to brief media.

A U.S. official said the two-day visit was meant to assess progress in the campaign to degrade and destroy IS, adding that McGurk met with a coalition of Arab and Kurdish commanders and fighters to discuss recent operations against the Islamic State group. ?

The official, who also spoke on condition of anonymity, said McGurk also visited Kobani to honor those who lost their life in defiance of the militants and meet with civilian administration officials as the one year anniversary of Kobani's liberation approaches.

A coalition of Arab and Kurdish fighters known as the Syrian Democratic Forces, which has the backing of the U.S., has emerged as the biggest fighting force against IS in northern Syria. The U.S. administration has sent a few dozen special operations forces to northern Syria to support it.

The Britain-based Syrian Observatory for Human Rights, an opposition group that monitors the conflict, also reported the visit by McGurk took place over the weekend. It said the delegation landed by helicopter in the Rmeilan air base in northeastern Syria.

Activists have reported that the American administration has recently been working on expanding the air base in Rmeilan village to serve as a military base for U.S. forces in northern Syria. Nasser Haj Mansour, a Kurdish defense official in Syria, also told the AP recently that U.S. personnel were renovating some airstrips built years ago by the Syrian government for small aircraft in case they are needed in the future.

U.S. officials have not confirmed the reports.

Associated Press writers Bradley Klapper in Washington and Zeina Karam in Beirut contributed to this report.