Defense ministers from the U.S.-led coalition against DAESH discussed the possibility of a ground incursion into Syrian two weeks ago, but they have not made a decision, an aide to Saudi Arabia's defense minister said on Monday.

"It was discussed two weeks ago in Brussels," Brigadier-General Ahmed Asseri said during a telephone interview from Riyadh. "It was discussed at the political level, but it wasn't discussed as a military mission. Once this is organized, and it has been decided how many troops, how they will go and where they will go, then we will participate in that. We need to discuss at the military level very extensively with the military experts to make sure that we have a plan."

Asseri also said Saudi Arabia was ready to strike DAESH from Turkey's southern İncirlik Air Base to which four Saudi fighter jets arrived last week. The jets have not yet conducted any attacks.At a joint press conference on Sunday with Danish Foreign Minister Kristian Jensen in Riyadh, Saudi Foreign Minister Adel Al-Jubeir warned that Saudi Arabia has prepared a "plan B" and said that if "the coalition decided to send ground troops into Syria, Saudi Arabia is ready to contribute."

The U.S. State Department said the Saudis had talked about the possibility of introducing ground forces into Syria to fight DAESH, but many issues needed to be discussed before a potential incursion.

State Department spokesman John Kirby said at a news briefing in Washington that Saudi Arabia had talked about "the potential of an introduction of some sort of ground force element in Syria," and that the United States would welcome their contribution in the fight against DAESH.

"But there's a lot that needs to be discussed in terms of what they would do, what their makeup would be, how they would need to be supported by the coalition going forward. So there's a lot of homework that needs to be done," Kirby said.

A U.S. defense official said supporting indigenous anti-DAESH forces on the ground was a key component of the U.S. strategy. "We will continue to provide equipment packages to vetted leaders and their units, so that over time they can make a concerted push into territory still controlled" by DAESH, the official said. "As a matter of policy, we won't comment or speculate on potential future operations."