What are the Prospects for the Syria Ceasefire?

Major questions remain over whether a partial truce in Syria, announced by the United States and Russia, will take hold as announced on February 27.

What are its prospects and what should the world expect from the key players in the conflict?

- Will the cessation of hostilities hold? -

The deal does not include the jihadist Islamic State group and Al-Qaida-linked Jabhat al-Nusra, providing a loophole for the Syrian regime and its Russian backers to continue attacks.

"Russia will fully exploit the loophole," said Firas Abi Ali, a Middle East analyst for IHS in London.

"They are going to pick and choose battles, probably some kind of strategic town under the claim that it is controlled by al-Nusra, and force the population into either accepting an advance by the government or being counted among the terrorists."

The regime may continue to encircle the rebel positions in the city of Aleppo, warned Yezid Sayigh, analyst at Carnegie Middle East Center in Beirut, so a monitoring system will be needed to clearly establish which side is violating the truce.

For the U.S. and Europe, the real measure of success will be if Russia and the regime stop the indiscriminate bombing of civilian areas, said Abi Ali.

If Russia does push Syrian President Bashar Assad to stick to the truce, his regime will be forced to "engage in real negotiations over transition, which it does not wish to do at all even if the terms are very favorable," said Sayigh.

- Why are the Russians pushing the Syrian government to accept a truce? -

The agreement is a way for Russia and President Vladimir Putin and the Syrian government to lock in its military advances, said Bertrand Badie, an international relations professor at Sciences-Po University in Paris.

"Putin had two options -- transform a military success into a diplomatic success, or offer Bashar the possibility of fresh military gains. He chose the first option because he needs to score points on a diplomatic level," said Badie.

The deal also creates a very difficult choice for the so-called "moderate" opposition groups fighting Assad's regime.

"They still have friendly borders with Jordan and Turkey which they can choose to withdraw behind and live to fight another day," said Abi Ali.

"Or they can stand alongside the Islamists and take their chances. Or they can try some kind of negotiation with Assad's forces, but none of these are very appealing options."

- Has the West abandoned the opposition rebels? -

Despite its virulent opposition to Assad and his regime, the West is equally worried about letting the Syrian state collapse completely, especially after witnessing the dangerous chaos that engulfed Libya after the overthrow of its dictatorship in 2011.

There is also frustration with the opposition.

"It has spectacularly failed to produce s credible leadership even after five years of support from Saudi Arabia and Turkey," said Abi Ali.

"It has not produced national bodies that are disconnected from a dangerous jihadist ideology, and that make it easier for the rest of the world to accept an agenda that eliminates the Islamists."

- What role will Turkey play now? -

Turkey has been one of the key backers of the opposition rebels and one of the most vocal opponents of Assad.

However, its primary concern has been the advance of Syrian Kurds, which it fears has emboldened Kurdish separatists in Turkey.

The truce deal puts Turkey in an "impossible situation," said Badie.

"Either they'll be the losers in all this and will be forced by the Americans to stop bombing the Kurds, or they will carry on and will be completely isolated."

Unlike the Cold War years, he added, these days U.S. allies often do whatever they want, meaning it is "far from certain" the Turks will obey the Americans.

- What does the truce mean for the war against the Islamic State group? -

"No one needs the Syrian war to continue as much as the Islamic State," wrote the Washington-based Soufan Group in a briefing note.

Any steps towards a truce allows Russia and the U.S. to increase pressure on the IS strongholds in Raqa and elsewhere.

"When the ceasefire map is drawn, the areas that will be easiest to define -- and thus, to continue to target by air -- will be those held by the Islamic State," said the Soufan Group.

The jihadist group sought to complicate the ceasefire process with a string of bomb attacks on Sunday near a Shiite shrine south of Damascus that killed 120 people, the deadliest attack since Syria's war began.