Syrian President Bashar al-Assad has said his government will not attend a Middle East peace conference unless Syria's concerns are addressed.
President Assad told the BBC that this meant primarily the return of the Golan Heights, occupied by Israel since 1967.
Mr Assad said no opportunity for peace should be squandered, but he saw little of the substance needed for success in US plans for a conference in November.
The talks are intended to focus on the Israeli-Palestinian conflict.
The US had said it would invite Syria, but only as a member of an Arab League committee dealing with the Israeli-Palestinian problem.
In his BBC interview, Mr Assad stressed that Syria still needed more clarification about the conference before it took its decision whether to attend or not.
"So far we didn't have the invitation and we didn't have any clarification about anything," he said.
"If they don't talk about the Syrian occupied territory, no, there's no way for Syria to go there.
"It should be about comprehensive peace, and Syria is part of this comprehensive peace. Without that, we shouldn't go, we wouldn't go."
Mr Assad also spoke about an Israeli air raid on northern Syria early in September which he said showed Israel's "visceral antipathy towards peace".
He said Syria reserved the right to respond to the attack - which he said targeted an unused military building - although he did not specify what that response should be.
"Retaliate doesn't mean missile for missile and bomb for bomb. We have our means to retaliate, maybe politically, maybe in other ways. But we have the right to retaliate," he said.
The comments were the first by the Syrian leader about the mysterious Israeli air incursion.
In the early hours of 6 September a number of Israeli jets appeared to enter Syrian air-space from the Mediterranean Sea.
Later unidentified drop tanks, which may have contained fuel from the planes, were found on Turkish soil near the Syrian border, indicating a possible exit route.
Israeli officials have not confirmed the incursion. The Syrian authorities previously said that the aircraft were driven off but that they fired their weaponry into a deserted area.