The UN Interim Force in Lebanon (UNIFIL) was established in 1978 in response to a surge in violence on the border between Israel and Lebanon. At the time, this Security Council resolution called for an immediate ceasefire and established UNIFIL to confirm the withdrawal of Israeli forces, restore peace and security, and assist the Lebanese government in restoring authority in the border area. But the peace was short-lived, with UNIFIL stepping in to provide protection and humanitarian assistance to the local population. The Israel-Hezbollah War in 2006 further necessitated the expansion of UNIFIL, to conduct military observations in addition to their peacekeeping duties.
LEBANON (UNIFIL)
Background
How UNIFIL Supports U.S. Interests
The U.S. has long had an interest in the region, particularly after the 2006 war re-escalated the conflict that had caused UNIFIL to deploy.
Budget
While the U.S. is the largest single contributor to the UN’s peacekeeping budget at 26.94 percent or $1.8 billion of the total budget, other UN member states pay the vast majority of costs and contribute 99 percent of the nearly 90,000 troops. Provided below is a breakdown of the cost of each mission and the U.S. contribution to UNIFIL.
Resources

UNIFIL Website
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Security Council Resolution 2591 (until August 2022)
Click here