(CNN)US Secretary of State John Kerry and Russian Foreign Minister Sergey Lavrov are meeting in Geneva to try and thrash out a deal on Syria, but after round after round of failed talks, can they really find common ground this time?
Syria talks: What Russia and the US agree and disagree on
Here's where things stand.
Attacking ISIS: The terror group is on everyone's blacklist, but US Secretary of Defense Ash Carter argues Russia has not focused enough on this: "The campaign against extremism, and particularly ISIL, which we are conducting ... the Russians aren't helping in that or participating in that," he told CNN's Christiane Amanpour. Instead, the coalition says, Russia has concentrated its attention on targeting the Syrian opposition.
A ceasefire: There have been temporary ceasefires in Syria in the past, and US President Barack Obama says Russia and the US "have had some productive conversations about what a real cessation of hostilities would look like, that would allow us both to focus our attention on common enemies," but a final agreement has so far proved elusive, hampered by what Obama calls "gaps of trust" between the two superpowers.
Which groups are terrorists: This is one of the major stumbling blocks in the way of a US-Russia deal on Syria. US President Barack Obama says there are "grave differences with the Russians in terms of ... the parties we support." Russian Foreign Minister Sergey Lavrov insists there needs to be a clearer distinction between legitimate opposition groups and militants: "I don't see any possibility of assuring a really durable, full-fledged ceasefire without the separation of healthy opposition forces from terrorists."
Who should be allowed to fight in Syria: Russia believes that only the Syrian regime and its supporters, including Iran and Russia itself have a legitimate reason to be carrying out airstrikes - Russia because it has been invited to participate by the Assad regime. Any others fighting in the country are violating Syria's sovereignty, it argues. "Many countries are represented by their military and army elements on the ground in Syria, but only the Russian and Iranian contingents are staying there upon consent from Damascus," Lavrov told RT News.
Turkey's incursion into Syria: Turkey's "Operation Euphrates Shield" campaign against ISIS along the Turkey-Syria border has seen the militants pushed out of the Syrian town of Jarablus. But it provoked "serious concern" about Syria's "sovereignty and territorial integrity" in Moscow, according to a statement posted on the Russian Foreign Ministry's website. Russian-Turkish relations took a hit after Turkey shot down a Russian warplane last year, but improved recently.
Aleppo: The besieged city is a big sticking point for Russia and the US. In months of protracted negotiations on Syria, the two nations reached agreement on 13 out of 15 questions that needed to be resolved before a deal could be reached. The two they couldn't see eye to eye on were both linked to Aleppo: humanitarian access to the city, and the ceasefire in the area. The US suspects Russia is holding out to give the Assad regime more time to capture rebel-held parts of the city, giving them a stronger claim to it when any future truce comes into effect.
Bashar al-Assad's future: Russia has invested heavily in keeping Syria's president in power, carrying out airstrikes that have helped its long-term ally retake territory from ISIS and other rebels. For the US - and many Syrians - Assad's removal is a non-negotiable step on the path to peace. But every time the US and its allies press Russia to tell Assad he has to go, they refuse.
What Syria will look like when the conflict is over: Russia's involvement in the brutal and lengthy battle for Aleppo is thought to be driven by a desire to ensure that Assad and his regime are left with some sort of "rump state" to rule over once a peace deal is done. That isn't likely to go down well with the US and the opposition High Negotiations Committee (HNC), which want to see regime change, rather than a divided Syria.