Let's review one of the key provisions of UNSC Resolution 1559 of 2004. Among other things, it called for "the disbanding and disarmament of all Lebanese and non-Lebanese militias" in Lebanon, including, of course, Hezbollah. Nothing was done. Then,

On January 28, 2005 UN Security Council Resolution 1583 called upon the Government of Lebanon to fully extend and exercise its sole and effective authority throughout the south, including through the deployment of sufficient numbers of Lebanese armed and security forces, to ensure a calm environment throughout the area, including along the Blue Line, and to exert control over the use of force on its territory and from it.

Again, nothing was done.

With the warfare raging between Israel and Hezbollah, some talk has begun among foreign ministries that an international force should be inserted into southern Lebanon to provide a buffer between Israel and Hezbollah, which would presumably relocate itself further north. Southern Lebanon would effectively become a demilitarized zone. Or, as an alternative narrative goes for this idea, the international force would take positive, even forceful, steps to disarm Hezbollah.

There are more than one severe problems with these proposals. One is that Israel, with overwhelming justification, does not trust the United Nations. The UN has a force in place in southern Lebanon, the United Nations Interim Force in Lebanon.

According to Security Council resolutions 425 (1978) and 426 (1978) of 19 March 1978, UNIFIL was established to: Confirm the withdrawal of Israeli forces from southern Lebanon;
Restore international peace and security;
Assist the Government of Lebanon in ensuring the return of its effective authority in the area.

Most recently the mandate of UNIFIL was extended until 31 July 2006 by Security Council resolution 1655 (2006) of 31 January 2006.

That means that UNIFIL's mandate expires this coming Monday. It will make no difference. UNIFIL has never showed the slightest interest in anything but watching Hezbollah attack Israel. If a future force is to be agreed to by Israel, it will have to meet the conditons set by Israeli Vice Prime Minister Shimon Peres, who was asked several days ago about the utility of an international force in southern Lebanon to stand between Israel and Hezbollah. Peres replied,

... The confrontation is not on the ground. It is in the air. If these U.N. forces can stop Hezbollah from firing missiles and rockets, that is one thing. If they are going to fight Hezbollah, fine. But there is no point to have people on the ground to observe the missiles flying overhead. That is useless.

Tragically, as Harvard law professor Alan Dershowitz points out, Kofi Annan has proven to be a huge obstacle to peace rather than peace's advocate.

If anyone wonders why the UN has rendered itself worse than irrelevant in the Arab-Israeli conflict, all he or she need do is read UN Secretary General Kofi Annan's July 20 statement. ...

Annan himself has a long history of one-sided condemnations of Israel. In March 2004, Annan "strongly condemned" Israel's targeted killing of Sheik Ahmad Yassin, the terrorist leader of Hamas, without condemning Yassin for his murderous actions or his organization for the murder of Jewish civilians. In December 2003, Annan "strongly condemned" Israel's assault on a Palestinian refugee camp where two gunmen were thought to be hiding. And in 2005, he issued the most tepid of statements--expressing "dismay"--at threats by Iran's president to "eliminate" Israel, a member nation of the UN. The list goes on and on. ...

This is a real test for the UN. If it cannot--or will not--distinguish between terrorists who target civilians and a democracy that seeks to stop the terrorism while minimizing civilian casualties, it has become part of the problem, rather than part of the solution.

There has been some talk about the UN outsourcing the international force to another treaty organization, with NATO being pretty much the only one mentioned. Since neither Lebanon, Hezbollah nor Israel has attacked a NATO member state, it's hard to see how such an intervention could be justified by the NATO charter, but the objection is almost moot. NATO states could individually commit forces on their own and form ad hoc command structures. But, says the NYT:

PARIS, July 24 — ... where will the troops come from?

The United States has ruled out its soldiers participating, NATO says it is overstretched, Britain feels its troops are overcommitted and Germany says it is willing to participate only if Hezbollah, the Lebanese militia which it would police, agrees to it, a highly unlikely development.

“All the politicians are saying, ‘Great, great’ to the idea of a force, but no one is saying whose soldiers will be on the ground,” said one senior European official. “Everyone will volunteer to be in charge of the logistics in Cyprus.” ...

There has been strong verbal support for such a force in public, but also private concerns that soldiers would be seen as allied to Israel and would have to fight Hezbollah guerrillas who do not want foreigners, let alone the Lebanese Army, coming between themselves and the Israelis.

... Israel wants [the international force] to keep Hezbollah away from the border, allow the Lebanese government and army to take control over all of its territory, and monitor Lebanon’s borders to ensure that Hezbollah is not resupplied with weapons.

Israel’s foreign minister, Tzipi Livni, laid out the goals in a meeting on Sunday with a British Foreign Office minister, Foreign Minister Frank-Walter Steinmeier of Germany and Foreign Minister Philippe Douste-Blazy of France. Ms. Livni told them that Israel’s goal was to disarm Hezbollah and that either the Israeli Army or an international force would have to do it, said officials familiar with the meeting.

The Europeans, by contrast, including Britain, France and Germany, envision a much less robust international buffer force, one that would follow a cease-fire and operate with the consent of the Lebanese government to support the deployment of its army in southern Lebanon.

Such a scenario would mean that Hezbollah, which is part of the Lebanese government, would have to be part of a decision that led to its own disarming and the protection of Israel, a scenario that European officials see as far-fetched.

I am reminded now of a little jody call we used to sing at morning PT: "MP, MP, don't arrest me, arrest that man behind that tree." Now consider:

The challenge of creating a viable international force to secure Israel’s border with Lebanon was captured by Nahum Barnea, a columnist for the Israeli daily newspaper Yediot Aharonot. The European foreign ministers were enthusiastic, he said. “They only had one small condition for the force to be made up of soldiers from another country,” Mr. Barnea wrote. “The Germans recommended France; the French recommended Egypt, and so on. It is doubtful whether there is a single country in the West currently volunteering to lay down its soldiers on Hezbollah’s fence.”

So the war will continue for the foreseeable future. The Lebanon-Israel-Hezbollah war is a tar baby no one else wants to slug. Here is the crux of the problem:

Any international force without the power to react to renewed outbursts of violence or to strike back if it found itself under threat would be as impotent as the current U.N. peacekeepers and unlikely to succeed at keeping Hezbollah away from the Israeli border.

More at that link.

Endnote: Since 1998, 253 UNIFIL troops have died on duty, including four this week who perished from Israeli fire), along with eight other staff - almost three KIAs per month for eight years. They have had a thankless job but the fact remains that of its three objectives, UNIFIL failed to accomplish two.