The relationship between Syria and the United States, a relationship marred by more than four decades of mutual distrust and accusations of aggression, deteriorated sharply following the Feb. 14, 2005 assassination of former Lebanese Prime Minister and opponent of Syrian involvement in Lebanon Rafik al-Hariri.

Immediately after the assassination, U.S. Secretary of State Condoleezza Rice pointed the finger at Syria, accusing Syrian and pro-Syrian Lebanese officials of creating an environment ripe for the attack.

"There is no doubt that the conditions created by Syria's presence there have created a destabilized situation in Lebanon," Rice told members of Congress, after pulling U.S. Ambassador to Syria Margaret Scobey from her post.

"Given their position in Lebanon, given their interference in Lebanese affairs, given the fact that their forces are there, given the terrorists that operate in southern Lebanon with Syrian forces in close proximity to them, does put on the Syrians a special responsibility for the kind of destabilization that happened there," Rice said.

In response, President Bush also demanded the immediate withdrawal of 15,000 Syrian troops left in Lebanon since the civil war. The president also threatened Syrian President Bashar Assad with increased international pressure and sanctions, if he failed to comply.

"The free world is in agreement that Damascus' authority over the political affairs of its neighbor must end," President Bush said.

Though Assad denied any involvement in Hariri's murder, Syria finally bowed to pressure and in April 2005 withdrew the last of its 15,000 troops from Lebanon.

But, ill feelings and distrust toward the United States and other western powers remained.

"Washington has imposed sanctions on us and isolated us in the past, but each time the circle hasn't closed around us," he told the Italian newspaper La Repubblica in 2005. "If, however, you ask me if I'm expecting an armed attack, well, I've seen it coming since the end of the war in Iraq."

A history of poor diplomacy
The dispute over Lebanon -- Hariri's murder and U.S. and Israeli accusations that Syria financed and armed Hezbollah fighters in the 2006 clash between Israel and Lebanon -- marks the latest scuffle in a long line of political clashes between the United States and Syria's Baathist regime. Though there have been instances of cooperation since 1974 when the two governments agreed to quash their differences over the Syrian-Israeli conflict, the two continue to harbor major differences.

Topping the list of U.S. criticisms against Syria is Damascus' alleged support of terrorist organizations. Syria has been prominent on the U.S. list of state sponsors of terrorism since its inception in 1979, according to the State Department, and the United States has responded by slapping export sanctions on Syrian goods and banning American aid over the years.

The United States accused the Syrian government of harboring the Palestinian militant group Islamic Jihad, following a Feb. 25, 2005 bombing in Tel Aviv, Israel that killed five people and injured more than 65. Islamic Jihad maintains part of its headquarters in Damascus.

"We do have firm evidence that the bombing in Tel Aviv was not only authorized by Palestinian Islamic Jihad leaders in Damascus, but that Islamic Jihad leaders in Damascus participated in the planning,'' White House press secretary Scott McClellan told reporters after the attack.

Syria also backs Hezbollah, a group that has in recent years repurposed itself into a political party, but one the United States still considers a terrorist organization credited with deadly attacks on Israel.

The 25,000-strong Muslim militia emerged during the Lebanese Civil War between Muslims and Christians and is the only remaining armed group allowed by the Syrian government to function in Lebanon, according to a New York Times article. The group has support from Lebanon's hundreds of thousands of Shiite Muslims, who consider it a social service organization of sorts.

Syria has maintained it has no connection with terrorists, and that American demands to implement U.N. Resolution 1559, which called for Syria's withdrawal from Lebanon, rang hollow given past U.N. resolutions calling for Israeli withdrawals from the disputed West Bank and Gaza Strip, the so-called "occupied territories."

"Syria has never, ever had any hand with any terrorists ... or anything that is happening in the occupied territories," Syrian Ambassador to the United States Imad Moustapha told the NewsHour. "What's happening in the occupied territories, a vicious circle of violence and counter violence, has everything to do with the Israeli policies there."

Moustapha's comments echoed decades of Syrian sentiment, which, according to Murhaf Jouejati, director of Middle East studies at George Washington University in Washington, D.C., sees the American embracing of Israel as anti-Arab.

"The Syrian and American perceptions of Israel could not be more different," Jouejati noted in a policy brief published by the Institute in January 2002. "Damascus views Israel as a rogue state if ever there was one. From the Syrian perspective, Israel has, at any given time, invaded all its neighbors, continues to occupy Arab land, and it openly admits to carrying out assassinations of individuals it perceives to be its enemies."

"Washington, on the other hand, views Israel as the country in the region that most resembles its democratic political system," according to Jouejati.

The Iraq question
The American government has also denounced Syria's refusal to adhere to U.N. oil sanctions on Iraq after the first Gulf War, during which time Syrian officials continued to do business with Saddam Hussein.

"[W]hat we saw prior to the war was that Syria was the number one violator of U.N. sanctions against Iraq and the number one source of illegal foreign exchange to the Saddam Hussein government," Danielle Pletka, former staff member of the Senate Foreign Relations Committee, told the NewsHour.

Syria was an outspoken critic when American forces launched a second attack against Saddam Hussein in 2003 and American officials have repeatedly accused Syria of allowing anti-American insurgents to cross the border between the two states.

"What we saw throughout the course of the war and prior to the war, was Syrian facilitation of the export of things like night vision goggles to the Saddam Hussein regime and other things," Pletka said, adding the government amounted to a "brutal dictatorship" held by a minority out of favor with the vast majority of Syrian people.

Syria's response
Even seemingly positive concessions made by Syria such as the capture and handover by the government of Sabawi Ibrahim al-Hassan al-Tikriti, half brother of Saddam Hussein and one of the United States' most wanted members of Iraq's former regime, and Syria pulling its troops out of Lebanon, have been met with skepticism.

In a 2005 New York Times article, Princeton University professor Michael Doran accused the Syrians of involvement in the Hariri killing, saying it was the latest chapter in Syria's cycle of provocation followed by conciliation.

"Ever since the 1980s," Doran said, "Syria has played this game of being both the arsonist and the fire department.

"They miscalculated how badly the Hariri assassination would backfire. Now, they're trying to curry favor with Washington to prevent the United States from coming down too hard on them. They've backed themselves into a corner, and they're trying to get out."

"Regardless of how they try to portray us, we will not fall into this trap," Ambassador Imad Moustapha said during his March 2, 2005 interview in response to such criticism. "We are not enemies of the United States of America. We don't need to create hostilities with this country. Actually, we have repeatedly invited the United States to constructively engage with Syria. We told them, if there are problems and issues between us and you, let's sit together, let's engage, let's put them on the table and let's see how we can find creative solutions."

Moustapha said a hostile relationship serves neither country.

"I don't think it's useful to Syria to be portrayed as an enemy to the United States," he added. "But ... also it doesn't serve the long-term interests of the United States to create more and more enemies in the Middle East."

Since Hariri's assassination, Assad, who was among the first international leaders to condemn the attack and who later was questioned as part of the investigation, agreed to pull troops out of Lebanon but not under pressure from the United States.

"There is an impression, which is wrong, that Syria is in a predicament and we have to find a way out," he told his parliament days before the pullout, according to Middle East Online.

"The natural place for Syrian forces is Syrian land," he said. "Withdrawal is in the interests of Syria."

-- Compiled by Kristina Nwazota for the Online NewsHour