ANKARA - Syrian government forces killed five Turkish soldiers in northwestern Syria on Monday, Turkey's defense ministry said, after Turkey deployed thousands of troops there to stem a Syrian government offensive.The attack, on a newly established Turkish military base in Taftanaz in Idlib province, happened a week after eight Turkish military personnel were killed by Syrian army bombardment. The two incidents were among the most serious confrontations between Turkish and Syrian troops in the nearly nine-year-long conflict in Syria, and Turkey has said it will drive back Syrian forces if they do not pull back by the end of this month."Their attacks against our posts have made an operation necessary," Omer Celik, spokesman for President Tayyip Erdogan's AK Party, told reporters in Ankara.The rapid advance by Syrian government forces in Idlib, the last major enclave of insurgents opposed to President Bashar al-Assad, has driven nearly 700,000 people from their homes towards the closed-off Turkish border.Turkey, which already hosts 3.6 million Syrian refugees, says it cannot absorb any more and is ready for military action to halt the Syrian government advances.It has poured 5,000 troops and convoys of military vehicles across the border, carrying tanks, armored personnel carriers and radar equipment to bolster its existing military positions.The defense ministry said Turkish forces retaliated on Monday for the attack in Taftanaz, which also wounded five soldiers who were flown by helicopter back to Turkey."Targets identified in the region were immediately targeted intensively...and the necessary response was given. The targets were destroyed and the blood of our martyrs was not left on the ground," the ministry said.A Turkey-backed Syrian rebel commander said the insurgents had also launched a military operation near the town of Saraqeb, south of Taftanaz, with Turkish artillery support.'WAR OF ATTRITION'As the conflict escalated in Idlib, Turkish and Russian officials met in Ankara for talks. The two countries back opposing sides in Syria, where Moscow's military intervention in 2015 helped swing the war decisively in Assad's favor.Celik said there were no concrete results from Monday's meeting, the second in three days, and the talks would continue.Russia and the Syrian government say they are fighting terrorists in Idlib, which is largely controlled by jihadist fighters."This is a war of attrition between Moscow and Ankara in which they are testing limits," said Galip Dalay, a visiting scholar at Oxford University.While there was a risk that the crisis could escalate further, Dalay said it could be managed with agreement between Ankara and Moscow on a buffer zone on the Syrian side of the border with Turkey, where displaced people could shelter.But the challenge of meeting the needs of the wave of uprooted people is growing daily."Since 1 December some 689,000 women, children and men have been displaced from their homes in northwest Syria," said David Swanson, a UN humanitarian spokesman. "That’s more than 100,000 people in just over a week."Swanson said the latest upheaval compounded an already dire humanitarian situation in Idlib, where 400,000 people were displaced between April and August last year by earlier fighting, many of them multiple times.