Thousands of Syrian refugees from the region have fled into Turkey to escape the biggest offensive in more than three months.

«The Russian Federation’s and China’s veto yesterday of a Security Council resolution that allows for humanitarian aid to reach millions of Syrians is shameful,» Pompeo said in a statement.

«To Russia and China, who have chosen to make a political statement by opposing this resolution, you have blood on your hands.»

Russia, backed by China, on Friday cast its 14th UN Security Council veto since the start of the Syrian conflict in 2011.

Vote at UN Security Council

The resolution, drafted by Belgium, Kuwait and Germany, would have allowed cross-border humanitarian deliveries for a further 12 months from two points in Turkey and one in Iraq. But Syrian ally Russia only wanted to approve the two Turkish crossings for six months and had proposed its own draft text.

Russia and China vetoed the text, while the remaining 13 members of the Security Council voted in favour. A resolution needs a minimum nine votes to pass, and no vetoes by Russia, China, the United States, Britain or France.

«The United States will remain committed to helping the voiceless, the hungry, the displaced, and the orphaned receive the humanitarian aid they require to survive no matter where they live,» Pompeo said.

Since 2014, the United Nations and aid groups have crossed into Syria from Turkey, Iraq and Jordan at four places annually authorized by the Security Council. In a bid to compromise with Russia, the Jordan crossing was dropped by Belgium, Kuwait and Germany from their draft.

Still time to reach aid agreement

The current authorization for the four border crossings in Turkey, Iraq and Jordan ends on Jan. 10, so the Security Council could still attempt to reach an agreement, though some diplomats acknowledged this could now be difficult.

Russian and Syrian jets have stepped up strikes on villages and towns around Maarat al-Numan, from which thousands of people have fled to the relative safety of the Turkish border fearing an imminent assault.

The Syrian army said it had gained more than 20 villages and hilltops, and was coming close to one of 12 Turkish observation posts in the northwest, part of a deal with Moscow and Tehran in 2017 to avert large-scale fighting in Idlib.

On Saturday, Russian jets hit a busy marketplace in Saraqeb city, east of Idlib, leaving at least eight dead and scores injured, two residents and one rescuer said.

Residents in the area said many villages were now deserted in a campaign that has since it first started in April has displaced more than 500,000 people, according to the United Nations and international relief groups.

«Many villages and towns have turned into ghost towns. Russia’s ‘scorched earth’ bombing is helping the army gain ground,» said Mohamad Rasheed, an activist from the area.

Syrians fleeing into Turkey

Russia and the Syrian army, which is loyal to President Bashar al-Assad, deny allegations of indiscriminate bombing of civilian areas and say they’re fighting al-Qaeda-inspired Islamist militants.

In the past week alone, at least 80,000 civilians fled and face harsh conditions during the start of winter, said the Union of Medical Care and Relief Organisations (UOSSM), a U.S.-based medical NGO. Turkey currently hosts some 3.7 million Syrian refugees, the largest refugee population in the world.

Medical facilities, already crippled by a year of attacks, are struggling to deal with the influx of wounded, it said. At least 68 medical facilities have been attacked since April, the NGO and other UN agencies have documented.

Western military sources said the latest bombardment was a prelude to a wide-scale ground offensive to take over rebel-held Idlib province.