Israeli soldiers fired tear gas to disperse scores of protesters who pelted the troops with stones along the border with Lebanon Friday, leaving some Lebanese demonstrators and troops suffering breathing problems.

The tension on the edge of the Lebanese border village of Kfar Chouba began earlier this week over the Israeli military digging in the area that Lebanon claims.

On Wednesday, a Lebanese villager tried to stop an Israeli bulldozer from digging a trench along the border. Once the villager’s legs were covered with sand as the bulldozer moved ahead, U.N. peacekeepers jumped in and convinced the driver to move back. Videos of the elderly man with his legs stuck in the sand dune went viral on social media.

Israel ended an 18-year occupation of southern Lebanon when its troops withdrew from the area in May 2000.

Friday’s protest took place on the edge of Kfar Chouba hills, which Beirut says is Lebanese land occupied by Israel. Kfar Chouba hills and the nearby Chebaa Farms, are areas captured by Israel during the 1967 Mideast War and claimed by Lebanon.

On Friday, some of the protesters tried to break through a fence in the rugged area overlooked by an Israeli military post. Israeli forces fired tear gas to disperse them while Lebanese troops and U.N. peacekeepers later moved in and pushed the protesters back.

“DO NOT CROSS THE BLUE LINE,” read a banner carried by a U.N. peacekeeper in Arabic, English and French, referring to the border drawn after Israel’s withdrawal in 2000. Israeli troops and several vehicles, including a heavily armored Merkava tank, were seen in the area.

Lebanese troops were on alert in the area and reinforcements were brought in.

In a statement, the Israeli military said protesters tried to damage a border barrier and threw stones at Israeli soldiers in the area. The military said forces responded with “riot dispersal means,” which typically means tear gas or stun grenades. The military said it “would not allow any attempt to violate Israeli sovereignty.”

UN Peacekeepers Working to Reduce Tensions

Andrea Tenenti, a spokesman for the U.N. peacekeeping for known as UNIFIL, said peacekeepers are on the ground working to decrease tension in the area.

“We have urged the parties to utilize our coordination mechanisms effectively to prevent misunderstandings, violations, and contribute to the preservation of stability in the area,” Tenenti said. He added that UNIFIL leadership is in contact with the parties, seeking a solution.

“We call upon both sides to exercise restraint and avoid actions along the blue line that may escalate tensions,” Tenenti told The Associated Press.

The protesters later held Friday prayers in the area and then tried to sneak in again, leading to more tear gas fire.

Friday’s tension came a day after the head of the U.N. peacekeeping mission in Lebanon, Maj. Gen. Aroldo Lazaro, chaired a meeting with senior Lebanese and Israeli officers at the U.N. headquarters along the border. The general appealed for restraint along the border and work on reducing tensions.

The Lebanon-Israel border has been relatively calm since Israel and Hezbollah fought a 34-day war in 2006. Despite that, there have been tensions.

In April, Israel launched rare airstrikes on southern Lebanon after militants fired nearly three dozen rockets from Lebanon at Israel, wounding two people and causing some property damage.