Unifil said of the two deaths on Monday: “We extend our sincerest condolences to the family, friends, and colleagues of those brave peacekeepers who gave their lives in service of peace.”
It said under international law, “all actors” had an obligation to ensure the “safety and security” on UN personnel.
“Deliberate attacks” on peacekeepers were “grave violations” of international humanitarian law, Unifil said.
“The human cost of this conflict is far too high. The violence, as we have said before, must end.”
After the soldier was killed on Sunday, the Indonesian Defense Forces (TNI) reaffirmed its commitment to the peacekeeping mission in Lebanon, according to the government-owned news agency Antara.
“We remain committed to carrying out our duties as part of the world peacekeeping mission under the mandate of the United Nations (UN) professionally and responsibly, while prioritising the safety of our soldiers,” Major General Aulia Dwi Nasrullah told Antara.
Antara named the soldier killed on Sunday as Chief Private Farizal Rhomadhon.
Unifil was created by the UN Security Council in 1978, and has since served as a buffer between Israel and Lebanon.
The peacekeeping force patrols the “Blue Line” – the de facto border between Lebanon and Israel, in collaboration with the Lebanese army.
Around 339 peacekeepers have been killed since the mission was established.
Despite a November 2024 ceasefire between Israel and Hezbollah, brokered after violence flared between the two over the war in Gaza, Israel has conducted near-daily strikes on Hezbollah targets.
It says the armed group has not abided by the terms of the ceasefire – under which Hezbollah was meant to disarm and leave its positions in the south – and has accused Unifil and the Lebanese army of not doing enough to remove its militants from the region.
Israel says its latest operation in southern Lebanon was intended to ensure the security of communities in the north.
Since the ceasefire began, 1,238 people have been killed in Lebanon, according to the Lebanese health ministry, including 124 children.
