U.S. Ambassador to Syria Robert Ford briefly crossed into northern Syria on Thursday to meet with Syrian opposition leaders.

It is Ford's first visit back to Syria since he left in February, 2012, when the U.S. embassy suspended operations in Damascus as the opposition effort to oust Syrian President Bashar al Assad developed into a full-blown civil war. Since then, Ford has become the Obama administration's point man on Syria and point of contact with the Syrian opposition.

A U.S. official confirmed Ford's secret visit, which occurred along the Turkey-Syria border. He briefly crossed into Syria to meet with opposition leaders before returning to Turkey. Ford did not go deep into Syria, according to the official.

"It was literally just across the border," the official said.

A State Department official confirmed that Ford had "spent some time" at a border crossing to discuss the situation in Syria with members of the Free Syrian Army and the Syrian opposition. Ford had gone to the border to participate in the U.S. government's delivery of Meals Ready to Eat (MREs) that the U.S. is providing to the Syrian Coalition and Supreme Military Council.

National Public Radio had earlier cited Syrian activists as saying Ford met with a rebel leader from Aleppo who thanked him for the delivery of some food aid being provided by the U.S.

Officials did not want to provide additional details of Ford's visit for security reasons. "Obviously, this a dangerous area so we don't want to get into the movement of diplomatic personnel," said the official.

Ford arrived in Turkey on Wednesday after having been in Moscow with Secretary of State John Kerry for meetings with Russian officials to get their support for a renewed effort towards a political solution for ending the civil war in Syria. Russia supports diplomatic initiatives for a transition but continues to provide support to the Assad regime.

The talks in Russia resulted in plans for an international conference to take place later this month at an undetermined location.

In Rome after the Russia visit, Kerry said of the conference, "There's a very positive response and a very strong desire to move to this conference and to try to find, at least exhaust, the possibilities of finding a political way forward."

Traveling in Rome on Thursday, Kerry said he had asked Ford to travel to Istanbul, Turkey, to engage in talks with the Syrian opposition that he described as having been "very productive."

On Wednesday, State Department spokesman Patrick Ventrell said Ford's meetings were designed to maintain engagement with the Syrian opposition and "to talk with them not only about our increasing support and their needs, but also about the opportunities for a political transition."

Kerry had just formally announced an additional $100 million in humanitarian aid for Syrian refugees.

More than a million refugees have fled the violence in Syria since it began in early 2011. The U.S. humanitarian aid package now totals $510 million.

The Obama administration is currently rethinking whether the U.S. should provide lethal assistance to Syrian rebels.