The withdrawal of most United States forces from Iraq this week is anything but the end of American military involvement in the Middle East. The latest focus of Washington's attention is Syria, where the United Nations says 5,000 people have been killed since the uprising erupted in March.

Before American (and probably British) soldiers are asked to give their lives in another Arab country, they are entitled to ask important questions.

Is Washington attempting to install a democratic government in Damascus? Or is it seizing the opportunity to bring down Iran's main Arab ally in advance of an American or Israeli attack on Iran?

Did the US have a hand in fomenting the rebellion that it says it now must support? Will war in Syria be as bloody as the Iraqi conflict, which the Brookings Institution says killed at least 115,000 Iraqis and nearly 5,000 Coalition troops and turned four million Iraqis into refugees? Will Syria suffer the kind of sectarian bloodbath that has yet to end in Iraq, despite the American pullout?

The Iraqi government clearly fears a Syrian conflict spilling across its border and is urging caution. "I know people must get their freedom and their will and democracy and equal citizenship," Iraqi prime minister Nouri al-Maliki said this week at the White House. "But I do not have the right to ask a president to abdicate. We cannot give ourselves this right." Obama weighed in: "There's no disagreement there." No disagreement? In August, Obama said: "For the sake of the Syrian people, the time has come for President [Bashar al] Assad to step aside."

Someone is fuelling violence in Syria with deliveries of weapons. The BBC has reported arms trafficking across the border from Lebanon, and a smuggler in Turkey told Guardian correspondent Ghaith Abdul Ahad: "We used to smuggle cigarettes coming from Lebanon via Syria. Now we only do weapons. Three shipments per day." The arms smuggling began at least last March, when Reuters reported that Syrian security captured truckloads of weapons from Iraq. (The Iraqi regime itself, which is as friendly to Iran as Syria is, was unlikely to have shipped the arms to undermine a fellow Shiite regime.)

Erik Prince, founder of Blackwater, a private security company that massacred 17 Iraqi civilians in Baghdad's Nissour Square in 2007, told Vanity Fair last January: "In Syria, we did the signals intelligence to geo-locate the bad guys in a very denied area." A month later, ABC News reported that Select PTC, a Blackwater subsidiary, "was involved in classified clandestine activities in countries around the world, including Pakistan, Afghanistan, Iraq, Syria and the Philippines, according to a former military intelligence officer …" American involvement with the Syrian opposition began much earlier, when the Bush administration publicly funded Syrian exile groups and awarded $6 million in 2006 to an anti-Assad television station, Barada TV.

Washington's support for regime change has escalated in recent months, backed by the region's major Sunni-led states - Turkey, Jordan, Saudi Arabia and Qatar. Syrians have legitimate grievances but they should be wary of inviting foreigners with their own agendas to assist them.

It didn't work out well in 1917, when some of them collaborated with Britain to expel their Turkish rulers and ended up with 25 years of European colonial domination.