A number of Irish troops have been moved from a UN base on the Golan Heights in Syria.
The Minister for Defence Simon Coveney has also confirmed that the next deployment of troops to the region has been delayed by two weeks.
The UN operation on the Golan Heights was reviewed following the abduction of dozens of peacekeepers by Islamic militants.
Mr Coveney said: "We've been quite quiet about it because it has been a redeployment of troops and we certainly didn't want what was happening to be publicly known, but it's complete now.
"Essentially, what's happened is that a series of UN posts, that would previously have been occupied, we have redeployed troops away from them.
"So Camp Faouar, which would have been the largest camp on the Syrian side, all of our troops have now left there. The Irish troops were the last to leave. It was an orderly withdrawal."
Five other countries contribute troops to the 1,200-strong UN force on the Golan: Fiji, India, Nepal, the Netherlands and the Philippines.
A UN spokesman said it had pulled back its peacekeepers to the Israeli side after Syrian fighters advanced near their positions.
The Syrian armed groups posed "a direct threat to the safety and security" of the troops from the UN Disengagement Observer Force (UNDOF), said UN spokesman Stephane Dujarric.
"All the UN personnel in these positions have thus been relocated to the Alpha side," said Mr Dujarric, referring to the Israeli-occupied sector.
The order came after Syrian rebels, including Al-Qaeda affiliate Al-Nusra Front, seized 45 Fijian UNDOF troops in late August before releasing them two weeks later.
They also clashed with 75 Filipino members of the force, who eventually fled a nearby outpost.
The UN spokesman said the situation on the Syrian side of the Golan "has deteriorated severely over the last several days" and that "armed groups have made advances in the area of UNDOF positions".