Syrian and Russian aircraft bombed several medical and first responder centres in Idlib over the weekend, in the build-up to a military push akin to previous government offensives near Damascus and the country’s south.
Barrages of missiles and barrel bombs on Sunday killed at least two children in the rebel bastion, a war monitor said.
The Syrian Civil Defence, also known as the White Helmets, shared an image on Twitter of what it described as a first response centre that was destroyed by air strikes.
The Union of Medical Care and Relief Organisations (UOSSM), a response organisation founded by Syrian doctors living outside the country, reported that three hospitals, two Syrian Civil Defense centres and an ambulance station were attacked in Idlib.
“It is distressing to see a rise in attacks on medical facilities that will ultimately affect thousands,” Dr Ghanem Tayara, chair of UOSSM International, said.
The build-up to the expected offensive is similar to government pushes on Eastern Ghouta near Damascus and in south Syria’s Deraa province. In both cases, medical centres were targeted in the initial bombardments as well as through the fighting, in contravention of international law.
The White Helmets, praised by the international community for saving lives but labelled a "terrorist" organisation by the Syrian state, were also targeted by regime air strikes.
Sunday marked the second day of bombardment on the rebel-held province and adjacent areas, after key powerbrokers in Tehran failed to reach a deal to avert a government assault.
The Syrian Observatory for Human Rights, a Britain-based monitoring group, said heavy attacks resumed on the north-western region near the Turkish border from midday.
"Regime helicopters dropped more than 60 barrel bombs on the village of Hobait in Idlib's southern countryside," Observatory head Rami Abdel Rahman said.
The raids killed at least two children and wounded six other people, he said.
In the neighbouring province of Hama, Russian jets carried out more than 10 strikes on rebel positions in the village of Al Latamneh, Mr Abdel Rahman said.
The raids wounded five rebels and knocked the village's underground hospital out of action, just a day after strikes damaged a similar health facility in Idlib's southern town of Hass.
The strikes eased off later on Sunday, the Observatory said.
On Saturday, some of the heaviest bombardment in weeks hit Idlib and nearby areas, killing at least nine civilians, it said.
More than half of Idlib is held by Hayat Tahrir al-Sham (HTS), an alliance led by Syria's former Al Qaeda affiliate, while most of the rest is held by rival rebels. The regime controls a south-eastern chunk.
HTS and rebels are also present in adjacent areas of the neighbouring provinces of Aleppo, Hama and Latakia.
The Observatory also reported assassinations, inter-factional violence and lawlessness in Idlib as the major government push looms.
Hundreds of families have fled Idlib's south-eastern areas since Saturday, when Russian and regime strikes on the region were the most violent in a month, the Observatory said.
The United Nations has warned that any military campaign in Idlib could push up to 800,000 people from their homes. Turkey is particularly concerned about hundreds of thousands of refugees fleeing north and west to try to cross the border.
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The leaders of regime allies Russia and Iran met with the president of rebel-backer Turkey in Tehran on Friday but failed to reach an agreement to avoid a military assault.
The rebel-held region of Idlib and adjacent areas are home to three million people, half of whom were displaced from other areas in the country, according to the UN.
Regime troops have for weeks been massing around Idlib, after President Bashar Al Assad's regime retook control of other areas of the country.
More than 350,000 people have been killed and millions displaced since Syria's civil war started in 2011 with the brutal repression of anti-Assad protests.
Meanwhile, a report by British politicians on Monday concluded that the international community’s failure to launch sustained military attacks in Syria resulted in “unacceptably high” loss of life, and also emboldened Iran and Russia to deepen their involvement in the seven-year conflict.
The cross-party group found that the UK had to bear a share of responsibility for the continuing use of illegal chemical weapons, in a conflict that has killed an estimated 400,000 people and forced 11 million to flee their homes.
British politicians, scarred by the experience of military intervention in Afghanistan and Iraq, voted against launching air strikes against the Syrian regime in 2013, in a crushing defeat for then prime minister David Cameron.
The UK was part of a joint and limited campaign of air strikes in April with the United States and France – without seeking parliamentary approval – but only after 85 chemical weapons attacks in Syria since 2013, the report by the Foreign Affairs Committee found. The three powers justified the attack on the basis of a “humanitarian intervention”.
In 2012, then US President Barack Obama, had warned of American military action if the Syrian regime crossed the “red line” of using chemical weapons, but drew back from attacks the following year in favour of a deal to destroy Syria’s chemical weapons’ stockpile.
“There has been a manifest failure to protect civilians and to prevent mass atrocity crimes in Syria,” said the 25-page report, Global Britain: The Responsibility to Protect and Humanitarian Intervention.
“It is clear from the catastrophe in Syria that when a state manifestly fails to protect its own citizens, non-intervention by the international community often results in appalling human suffering and widespread loss of life.”
The committee called on the UK government to draw up an early intervention strategy to prevent atrocities abroad. Its call for an independent inquiry to examine the price of inaction over the Syrian war has been ruled out by the government.
In a letter to the committee, Foreign Secretary Jeremy Hunt – who backed air strikes in 2013 – said: “I regret that failing to act militarily at that time we may have emboldened the regime and encouraged other countries to enter the conflict more forcefully on the side of the Syrian regime.”
UK politicians had called for intervention in Syria as early as 2011, to create no-fly zones or humanitarian corridors. Deadlock at the United Nations Security Council – where Russia has used its veto power at least a dozen times over Syria – stymied a unified international effort to prevent atrocities against the civilian population.
“Inaction allowed the regime, with the help of Iran and Russia, to capture many areas,” Haid Haid, from London’s International Centre for the Study of Radicalisation, told the committee.
The MPs said a major inquiry into British military intervention in Iraq had examined the cost of intervening in foreign conflicts, but the consequences of not acting were less well-known.
Committee chairman Tom Tugendhat, of the Conservative party, said: “The consequences of inaction can be devastating. With the situation in Idlib reaching crisis point, action to prevent mass atrocities is ever more urgent.”