MUNICH (Reuters) - Russian Prime Minister Dmitry Medvedev raised the specter of an interminable 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.

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Medvedev, speaking to Germany’s Handelsblatt newspaper on the eve of talks between major powers on Syria 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.”

“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.

Hilighting the rift in perceptions between Russia and the West, French President Francois Hollande Assad to leave power - something Russia has always rejected.

The Munich talks appeared to hold out little promise of progress. “This meeting risks being endless and I fear the results will be extremely small,” one diplomat said.

Russian Foreign Minister Sergei Lavrov said 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.

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 the Munich meeting.

“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?”