The UN investigation into Israel's Gaza flotilla raid that left 8 Turks and one Turkish-American dead opens today with Turkey insisting that Israel bears full responsibility for the deaths and Israeli Defense Minister Ehud Barak saying a Turkish aid group's attempt to breach the economic blockade of Gaza was a "deliberate provocation."

The UN investigation will start with Secretary General Ban Ki-moon meeting with the four-member panel, which includes both an Israeli and a Turkish representative. The panel will investigate the fatal Israeli raid on a Gaza-bound aid boat.

“I am grateful for the spirit of constructive engagement that has made this unprecedented panel possible,” Mr. Ban said Monday, hinting at an Israel-Turkey rapprochement that both sides as well as common ally Washington seem keen to achieve. “I am confident that this initiative will contribute to regional stability.”

Israel’s participation in the UN probe is unprecedented, coming after years of criticizing UN bias and resisting intense international pressure to change its heavy-handed approach. But it also came with key conditions – among them, says Israel, Mr. Ban’s agreement behind the scenes that the probe would not directly question Israeli soldiers.

Yesterday, Ban denied making that promise, throwing into question Israel’s cooperation. An Israeli government statement said: "Prime Minister [Benjamin] Netanyahu makes it absolutely clear that Israel will not cooperate with and will not take part in any panel that seeks to interrogate Israeli soldiers."

The last-minute dispute signals the myriad red lines and potentially conflicting demands that the panel will have to navigate as it takes up its work today.

The UN panel is expected to examine internal Israeli and Turkish investigations and report back to Ban by mid-September. Israel’s military completed its probe of the incident several weeks ago, while an inquiry into the raid’s legality headed by former Israeli Supreme Court judge Jacob Turkel began questioning top Israeli leaders this week.

Some in Israel are seeking a broader mandate for the UN inquiry, including an examination of the Turkish NGO behind the flotilla – which some Israelis allege has militant links – and the necessity of Israel’s naval blockade of Gaza, which Israel says is needed to prevent Hamas from receiving weapons.

The Turkish government, which is under domestic pressure to display its achievements before a Sept. 12 referendum, is likely to press for an apology and demand compensation.

“If it’s money, it’s not so hard. We have money,” says Alon Liel, a former Israeli diplomat in Turkey who helped negotiate compensation for Turkish victims during Israel’s war with Lebanon in the 1980s. “But when it’s honor, that’s much harder.”

Turkey has also asked that the panel report directly to the UN Security Council, whose rotating presidency Turkey will assume in September.

The UN inquiry will be chaired by former New Zealand Prime Minister Geoffrey Palmer and Alvaro Uribe, who just stepped down as Colombia’s president. Mr. Uribe’s addition as vice chair was seen by many as crucial to Israel’s agreement to join the panel.

Uribe knows well the kind of criticism Israel faces for fighting militant groups. In fact, after one of the many raids Uribe’s Colombia made in its successful fight against the narcotrafficking guerrilla group known as FARC, Venezuelan President Hugo Chavez shunned it as the “Israel of Latin America.”

Mr. Palmer and Uribe will be joined on the four-member panel by Ozdem Sanberk of Turkey and Israeli representative Joseph Ciechanover, Ban announced over the weekend. Mr. Sanberk is a veteran diplomat with extensive experience at Turkey’s foreign ministry and the United Nations. Mr. Ciechanover, the former chairman of the board of El Al airlines, previously served as general counsel to Israel’s defense ministry and director-general of Israel’s foreign ministry.

But both sides appear committed to arresting the acute slide in Israel-Turkish relations brought on by the raid, and repairing Israel’s most important regional alliance.

The alliance has benefited both countries over the years and has also been seen as crucial to regional stability by a key regional player: the United States, an ally of both Turkey and Israel.

It was perhaps those broader benefits that brought both sides back from the brink. When Turkish officials visited Washington soon after the flotilla incident, “the atmosphere … was not the most cordial,” says Suat Kiniklioglu, a senior member of the ruling Justice and Development Party who was part of the delegation.

Even President Bashar al-Assad of Syria, a sworn enemy of Israel, suggested that repairing ties might be in everyone’s best interest. Failing to do so would “without doubt affect the stability in the region,” he said.

Turkey has long been Israel’s best Muslim friend in a hostile neighborhood. Over the past 15 years, the duo has established strong military cooperation and trade ties worth $3 billion.

Turkey, the successor of an empire that once spanned three continents, has of late sought to recapture regional stature as a mediator.

But Turkey has become increasingly frustrated with Israel over its policies toward the Palestinians, particularly the 2009 offensive in Gaza. The last straw was Israel’s raid on the Turkish flagship of a ‘Freedom Flotilla’ seeking to challenge the three-year Israeli blockade of the impoverished territory.

Turkish Prime Minister Recep Tayyip Erdogan called it a massacre that “deserves every kind of curse.” That harsh rhetoric, coupled with Turkey’s decision to recall its ambassador to Israel indefinitely, led some to speculate that the Islamic-rooted government was forsaking the mediator role it had so carefully carved out – perhaps to boost its standing at home.

“I think Turkey really mismanaged things after the flotilla,” says Soli Ozel, an international relations instructor at Istanbul’s Bilgi University. “They overreached. If you want to play in the big leagues, you’ve got to be able to contain your temper. You don’t make your foreign policy hostage to your domestic politics.”

But Turkey now appears eager to demonstrate to its allies, both in the West and the Muslim world, that it remains a trustworthy arbiter.

“Turkey wants to prove that there is no axis shift in its foreign policy. The prime reason for Turkey supporting the commission is this,” says Mansur Akgun of the Turkish Economic and Social Studies Foundation, an Istanbul-based think tank. “Turkey also wants to have a stable environment around it and it’s not possible to solve the problems of the region without good relations with Israel.”