Q+A: Are odd couple Turkey and Israel breaking up?

Lebanese leftists and Palestinians carry a giant Turkish flag during a protest against Israel's interception of aid ships sailing to the Gaza strip in front of the United Nations headquarters in Beirut, May 31, 2010.

ANKARA (Reuters) - A raid by Israeli marines on a Gaza-bound aid convoy has plunged already crumbling ties between Israel and its Muslim ally Turkey to an historic low, with the ruling AK party saying relations will never be the same.

The killing of more than 10 activists on a Turkish vessel stirred protests in Istanbul. A senior Israeli officer said most of the dead were Turks. Prime Minister Tayyip Erdogan called the raid "state terrorism."

Ankara has canceled joint military exercises, recalled its ambassador to Israel and called for an emergency meeting of the U.N. Security Council.

Below are some questions and answers on how the raid can affect Turkey-Israel ties.

IS THIS THE DEATH KNELL FOR TURKEY-ISRAEL TIES?

Israel and Turkey have a long and close military alliance and economic relationship. Bilateral trade reached $2.5 billion in 2009, with Turkey buying military hardware from the Jewish state. Analysts say their relationship, though complex, offers too many advantages to both countries to be forsaken easily.

Turkish and Israeli officials have in the past said they will remain allies as long as their interests are aligned. The two countries share intelligence on common security threats such as al Qaeda. However, since Erdogan's Islamist-leaning AK Party took office in 2002 relations have been strained, notably as Turkey deepened ties with fellow Muslim countries, including Iran and Syria.

With Turkey's prospects for joining the European Union growing more elusive, some analysts have wondered whether Turkey was turning East instead of West under Erdogan.

Huseyin Celik, an AK Party spokesman, said: "Our relations with Israel will never be the same."

HOW IS TURKEY LIKELY TO REACT?

Turkey has warned of possible "irreversible consequences in our relations." With public anger seething, Erdogan is likely to take a harsh line against Israel.

Erdogan became a hero across the Islamic world for publicly criticizing Israeli policy toward Palestinians. With an election due by July next year, and opinion polls showing high unemployment has dented support, a strong stand against Israel could go down well with voters.

Foreign Minister Ahmet Davutoglu, who has called Israel's raid an "act of piracy," traveled to New York, where non-permanent member Turkey will seek during a U.N. Security Council meeting later Monday to gather international condemnation against Israel.

Deputy Prime Minister Bulent Arinc said Turkey will seek international legal action against Israel as the raid took place in international waters.

HOW WILL THE FALLOUT AFFECT U.S. POLICY IN THE MIDDLE EAST?

The alliance between Turkey and Israel, two regional military heavyweights, has been a boon to U.S. diplomacy in the Middle East. Any breakdown would complicate the equation.

The United States has long sought Turkey's soft power as a secular, democratic Muslim state to counter Islamist militancy in the region. U.S. President Barack Obama, who needs Turkey's support from Iraq to Afghanistan, must balance backing for Israel with understanding for an angry Turkey, a NATO member.

Turkey has been a major player in Arab-Israeli peacemaking and mediated indirect talks between Syria and Israel. The talks were suspended after an Israeli incursion into Palestinian-run Gaza in January 2009, and prospects for renewing those talks seem dim.

While welcoming Turkish mediation with Syria, Washington has clashed with Turkey over how to tackle the Islamist Hamas, which controls the Gaza Strip. Washington wants to isolate Hamas, while Ankara feels the Islamist group should not be excluded.

HOW DID IT GET THIS BAD?

Analysts say ties deteriorated sharply after Israel's Gaza offensive, which Erdogan called a crime against humanity and prompted Turkey to bar Israel from participating in a NATO military exercise. Erdogan further alienated Israel by hosting Iran's President Mahmoud Ahmadinejad, and referring to him as a "good friend." Israel was angered by Turkey's attempts to mediate in Tehran's nuclear dispute with the West, arguing such steps undermined international efforts to isolate Tehran. Analysts have also said anti-Semitism in Turkey is on the rise after the war in Gaza.

(Additional reporting by David Cutler, London Editorial Reference Unit)