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As international diplomats get ready for a new round of talks on Syria, they're struggling with some pretty fundamental questions. Which of the rebels who are fighting in Syria are actually terrorists? Which Syrians could be part of a future government? And how can all the countries that are supporting proxies in the Syrian war work together to calm a situation and stay focused on the threat of ISIS? NPR's Michele Kelemen reports.
MICHELE KELEMEN, BYLINE: When Russian war planes started bombing Syria a couple of months ago, Foreign Minister Sergey Lavrov offered a sweeping view of the militants they were targeting.
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SERGEY LAVROV: If it looks like a terrorist, if it acts like a terrorist, if it walks like a terrorist, if it fights like a terrorist, it's a terrorist, right?
KELEMEN: British foreign secretary Philip Hammond says the trouble is that while Russia says it's bombing terrorists, it is instead, in Hammond's words, bombing our friends. He says one of the goals of this weekend's meeting in Vienna is to hash out just who is a terrorist, and that should help narrow Russia's target list to ISIS and al-Qaida linked groups and encourage Russia to stop launching airstrikes against more moderate rebels.
There are 19 countries involved in the talks, though, all backing different sides in Syria, so diplomats say it will require a lot of give-and-take just to agree on who are the bad guys and who can be part of eventual peace talks. Secretary of state John Kerry's philosophy is to keep everyone at the table. That also seems to be the strategy of U.N. envoy Staffan de Mistura, who just briefed the Security Council.
STAFFAN DE MISTURA: My message was one word - momentum. The momentum in Vienna needs to not be missed.
KELEMEN: De Mistura has tried for years to get the warring sides in Syria to agree to local truces and give some space to aid groups trying to reach millions of people uprooted by the war. He says the U.N. can't do much without the big powers reaching common ground.
DE MISTURA: My job is to make sure that big countries like Russia Federation and Saudi Arabia and Iran come around the table and come up with some political process. Then we pick up the pieces, and we run with it.
KELEMEN: Russia's Foreign Minister is warning against what he dismissed as abstract ideas about changing the regime in Syria, saying if that's what the U.S. and its allies still have in mind, the meeting in Vienna won't be a success. Michele Kelemen, NPR News, Washington. Transcript provided by NPR, Copyright NPR.