The US and Turkey are close to an agreement on joint military action against the Islamic State (ISIS) terrorist group in northern Syria, according to the Wall Street Journal.

Citing officials from both the U.S. and Turkey, the paper reported that the proposed deal would allow the U.S. and its coalition partners access to Turkish air bases for launching air strikes.

The agreement would also provide for a no-fly zone along a section of the border between Turkey and Syria, which would be off limits to Syrian government aircraft and provide protection for “moderate” Syrian rebels and refugees fleeing the country’s civil war.

Turkey has already agreed to allow 2,000 Syrian rebels from “moderate” streams to be trained on its soil, and has sent members of its special forces to northern Iraq to train Kurdish Peshmerga fighters.

The Wall Street Journal reported that Turkey had proposed a far more extensive no-fly zone over northern Syria, but the Obama administration refused, saying that the proposal would constitute an act of war by the US against the government of Syrian President Bashar al-Assad.

US officials told the paper that talks between the two nations were still in a preliminary stage, and a final deal may not be agreed upon for weeks.