MUNICH (Reuters) – Russian Prime Minister Dmitry Medvedev raised the specter of a permanent or a world war if powers failed to negotiate an end to the conflict in Syria and warned against any ground operations by U.S. and Arab forces.

Medvedev, speaking to Germany’s Handelsblatt newspaper on the eve of a security conference in Munich, said the United States and Russia must exert pressure on all sides in the conflict to secure a ceasefire.

Asked about Saudi Arabia’s offer last week to supply ground troops if a U.S.-led operation were mounted against Islamic State, he said:

“This is bad as a ground offensive usually turns the war into a permanent one. Just look at what happened in Afghanistan and many other countries. I don’t need to remind you what happened in poor Libya.”

“The Americans and our Arab partners must think well: do they want a permanent war?” It would be impossible to win such a war quickly, he said according to a German translation of his words, “especially in the Arab world, where everybody is fighting against everybody”.

“All sides must be compelled to sit at the negotiating table instead of unleashing a new world war.”

Russia is carrying out bombing sorties around the key city of Aleppo, in support of advances by troops loyal to President Bashar al-Assad. U.S. and other Western air forces are also involved in air strikes in northern Syria.

THE “PRIZE” OF ALEPPO

Capturing Aleppo, Syria’s biggest city before the war but now divided between rebel- and government-held sectors, would represent a major military victory for Assad and a symbolic prize for Russia.

Russian Foreign Minister Sergei Lavrov said on Thursday that Moscow had submitted proposals for implementing a ceasefire in Syria and was waiting for a reaction from international powers.

Lavrov was speaking ahead of a meeting in Munich with U.S. Secretary of State John Kerry to discuss Syria.

Members of the United Nations Security Council pressed Russia on Wednesday to stop bombing Aleppo in support of the Syrian military offensive and allow humanitarian access ahead of a meeting of major powers in Germany on the conflict.

“You have no one power that can act alone,” Medvedev said. “You have Assad and his troops on one side and some grouping, which is fighting against the government on the other side. It is all very complicated. It could last years or even decades. What’s the point of this?”

(Reporting by John Irish, reporting by Joseph Nasr; editing by Ralph Boulton)