"I hereby declare that we will strike regime forces everywhere from now on regardless of the Sochi deal if any tiny bit of harm is dealt to our soldiers at observation posts or elsewhere," Erdogan told a meeting of his ruling party in parliament.

The latest threat comes after more than a dozen Turkish soldiers were killed in regime shelling in the northwestern province of Idlib - the last rebel stronghold in Syria.



On Tuesday, the UN expressed concern for the humanitarian situation in the region amid widespread regime bombardment.



"In just 10 weeks, since 1 December, some 690,000 people have been displaced from their homes in Idlib and surrounding areas," a spokesman for the Office for the Coordination of Humanitarian Affairs said.



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"This is, from our initial analysis, the largest number of people displaced in a single period since the Syrian crisis began almost nine years ago," David Swanson said.



The UN expressed concern for civilians as Idlib is hit by freezing temperates amid shortages of tents, food, and clean water.



The regime of Bashar al-Assad lost huge swathes of the country to rebels as a result of a conflict that erupted following the repression of what started off as peaceful anti-government protests in 2011.



The brutal tactics of the Assad regime against the uprising triggered an armed rebellion fuelled by mass defections from the Syrian army, leading the country to civil war.



According to UN figures, the Syrian conflict has caused the greatest displacement crisis in the world, with at least 5.5 million people fleeing the country and more than 6 million more displaced inside Syria.



The Syrian war is considered to have caused the biggest wave of displacement since World War II.







Agencies contributed to this report.



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