ANKARA, Turkey — Turkey said it retaliated Monday after “intense” shelling by Syrian forces killed five of its soldiers and wounded five others in Syria’s northern Idlib province, a marked escalation a week after a similarly deadly clash between the two sides.

The exchange of fire came as a Russian delegation held a second round of talks in the Turkish capital of Ankara to discuss the fighting in Idlib province, which has uprooted more than a half-million people in the past two months. No statement was issued at the end of the talks.

The fighting led to the collapse of a fragile cease-fire brokered by Turkey and Russia in 2018. Turkey supports the Syrian rebels, while Russia heavily backs the Syrian government’s campaign to retake the area, which is the last rebel stronghold in Syria.

A U.N. official said the number of people displaced by the violence since Dec. 1 reached nearly 700,000.