On Tuesday July 25th, Israel bombed a UN compound in South Lebanon killing Canadian, Finnish, Austrian and Chinese nationals. The UN warned Israel with at least 10 separate telephone that repeated aerial and artillery attacks had already landed at or dangerously close to their post in Khiam and an internal UN report on the incident says there were more than 20 aerial and artillery attacks on the post on Tuesday, including four artillery rounds that directly hit the UN position an hour before the fatal guided bomb attack. The report also said that, each time the UN called to complain, the Israeli officer they talked to promised that the attacks would stop but the strikes continued.
Kofi Annan, the United Nations secretary general, condemned Israel, saying he was shocked by the "apparently deliberate targeting" of the post, and called for it to investigate the incident.
On Wednesday, the US blocked the U.N. Security Council from issuing a statement that would have condemned the bombing as much of the right-wing Israeli media used Annan's condemnation as an excuse to lash out at the UN.

UN Ambassador Bolton Blocks Measure Condemning Lethal Israeli Attack on UN | Israel under fire for killing UN monitors | Israelis Kill UN Peacekeepers - Halutz Commits to War Crimes