THE world has plunged into a “new Cold War”, the Russian prime minister said on Saturday, as Moscow came under attack at a global security gathering over its targeting of moderate rebels in Syria.

US Secretary of State John Kerry told the Munich Security Conference that “the vast majority of Russia’s attacks (in Syria) have been against legitimate opposition groups.”

“To adhere to the agreement it made, Russia’s targeting must change,” he said, referring to the international deal forged on Friday, in which 17 countries agreed to seek a “cessation of hostilities” in Syria within a week.

He spoke shortly after Russian Prime Minister Dmitry Medvedev said the world had “slid into a new period of Cold War.”

“Almost every day we are accused of making new horrible threats either against NATO as a whole, against Europe or against the US or other countries,” Medvedev said. “They make scary movies where Russia starts a nuclear war. I sometimes wonder: are we in 2016 or 1962?”

His comments came as Syrian government forces, backed by Russian jets, were poised to advance into the Islamic State stronghold of Raqqa province.

An advance into Raqqa would re-establish a Syrian government foothold in the province for the first time since 2014 and may be aimed at pre-empting any move by Saudi Arabia to send ground forces to fight Islamic State militants in Syria.

Russia is pressing ahead with its four-month-old air campaign in support of President Bashar al-Assad ahead of “a cessation of hostilities” agreed by major powers on Friday. The agreement is due to come into effect in a week.

The Syrian army has announced the capture of more ground in the northern Aleppo area, where its advances backed by allied Lebanese Hezbollah and Iranian fighters have cut the main rebel supply route from Turkey into opposition-held parts of Aleppo.

If its forces retake Aleppo and seal the Turkish border, Damascus would deal a crushing blow to the insurgents who were on the march until Russia intervened last September, shoring up Assad’s rule and paving the way for the current advances.

The cessation of hostilities agreement falls short of a formal ceasefire, since it was not signed by the warring parties — the government and rebels seeking to topple Assad in the five-year-long war that has killed 250,000 people.

Russia has said it will keep bombing Islamic State and the al Qaeda-linked Nusra Front, which in many areas of western Syria fights government forces in close proximity to insurgents deemed moderate by Western states.

Gulf states that want Assad gone from power have said they would be willing to send in troops as part of any US-led ground attack against Islamic State. US Defense Secretary Ash Carter said on Friday he expected Saudi Arabia and the United Arab Emirates to send commandos to help recapture Raqqa.

Saudi Arabia’s foreign minister, Adel al-Jubeir, said in an interview published on Saturday that Russia’s military interventions will not help Assad stay in power. “There will be no Bashar al-Assad in the future,” he told a German newspaper.

The complex, multi-sided civil war in Syria, raging since 2011, has drawn in most regional and global powers, producing the world’s worst humanitarian emergency and attracting jihadist recruits from around the world.

A US State Department spokesman said on Friday that Assad was “deluded” if he thought there was a military solution to the war.

Two Syrian rebel commanders told Reuters on Friday that insurgents had been sent “excellent quantities” of Grad rockets with a range of 20km by foreign backers in recent days to help confront the Russian-backed offensive in Aleppo.

Foreign opponents of Assad including Saudi Arabia and Turkey have been supplying vetted rebel groups with weapons via a Turkey-based operations centre.

Some of these groups have received military training overseen by the US Central Intelligence Agency. The vetted groups have been a regular target of the Russian air strikes.