George Ourfalian / REUTERS Dead animals, killed by what residents said was a chemical-weapon attack, in Khan al-Asal, near the Syrian city of Aleppo, on March 23, 2013

After a six-month delay, U.N. chemical-weapons experts have finally arrived in Syria to find out what exactly happened in Khan al-Asal, near the city of Aleppo, on March 19, when 31 people died in what appears to have been a chemical-weapon attack. The investigative team will stay for at least a week, visiting Khan al-Asal as well as two other sites, which are thought to have been hit by similar attacks, though for security reasons their locations have not been revealed.

In Khan al-Asal, the government claimed that “terrorists” — its blanket term for antiregime rebels — had fired a “missile containing a chemical substance” at the village in retaliation for residents’ support of the government, and asked for a U.N. investigation. The rebels accused the government of attacking its own people in order to smear the opposition and echoed the call for an impartial investigation. The investigation team, including weapons experts from the Organisation for the Prohibition of Chemical Weapons, has been on standby since April, waiting on negotiations about the kind of access Damascus is willing to permit. Investigators may finally be in Syria, but they are unlikely to reach the kind of closure that the victims’ families, the government, the rebels or even the international community seek.

(MORE: Syria’s Civil War: The Mystery Behind a Deadly Chemical Attack)

To begin with, the team’s objective is only to determine whether or not chemical weapons were used, not how and not by whom. Even under the best circumstances — unfettered access, immediately following the attack — the findings were likely to be disappointing. Who wouldn’t want to be able to point a finger when it comes to the deployment of a weapon that is universally abhorred? Six months on, the circumstances are significantly less than ideal — physical traces of the agents are likely to have disappeared by now, forcing investigators to depend on available medical records and interviews with survivors, both of which are vulnerable to manipulation.

“If it is about going in and coming back with definitive confirmation that chemical weapons have been deliberately used, there is reason to be skeptical that the investigation will bear fruit,” says chemical-weapons expert Jean Pascal Zanders. That doesn’t mean it’s a waste of time. The presence of the investigation team in Syria serves as a deterrent and sends a strong signal about the unacceptability of chemical warfare to all sides in the conflict, says Zanders, who heads the Trench, a new initiative that looks at the future of chemical-and-biological-weapons disarmament. And if, despite the odds, the team does come back with facts to support the allegation that weapons were used, then “even if no blame is apportioned, the U.N. Security Council cannot avoid making a statement to condemn the use of such weapons, irrespective of the culprit.” If such a resolution is passed, it will put enormous pressure on supporters of both sides in the conflict to make sure that neither the regime nor the rebels resort to such weapons in the future.

Early accounts of the attack suggested chlorine gas, but subsequent reports from Western intelligence agencies, based on interviews with victims that were smuggled out by rebels, indicated nerve agents like sarin, the gas used by members of Japanese cult Aum Shinrikyo to attack commuters in Tokyo in 1995. But after six months and a hot summer, neither substance will remain, Zanders says. Chlorine would have dissipated immediately. Sarin, which evaporates at the same rate of water, can leave a distinct chemical signature as it breaks down, a reliable indication of its onetime presence in the area. That said, it would be impossible to ascertain whether evidence of such trace elements points to a weaponized form of sarin or simply an explosion at a toxic chemical depot. Forensic experts investigating the Tokyo attack were able to find traces of sarin gas at an Australian farm owned by the Japanese cult 18 months later, but they couldn’t confirm whether it came from a lab experiment or large-scale production.

(MORE: Syria’s Lurking Terror: A History of Sarin Gas)

Whatever the results of this limited investigation, things are unlikely to substantially change in Syria as a result. A year ago U.S. President Barack Obama warned that the use of chemical weapons by the Syrian government would be a “redline” for U.S. intervention. But like the meaning of coup in regards to the Egyptian military’s role in the country’s current crisis, the deployment of such an accusation will be calibrated to suit political imperatives.

Even if it were somehow proved that the regime had used chemical weapons in a limited manner six months ago, as some intelligence agencies attest, would Obama really be willing to up the ante in a war that has already proved to be a redline for the American public? “As long as they keep body count at a certain level, we won’t do anything,” an American intelligence admitted to Foreign Policy in a recent interview. And what if the investigation were to point to the possibility that rebel fighters deployed chemical weapons? Former CIA second-in-command Michael Morell has already expressed fears of Syria’s vast arsenal of chemical weapons falling into rebels’ hands as one reason to go slowly in the pursuit of regime change. The Syrian government’s weapons, he said in an interview with the Wall Street Journal, “are going to be up for grabs and up for sale” like they were in Libya, with potentially disastrous results. The U.N. investigation into chemical-weapons use in Syria sets an important precedent, but it’s unlikely to answer the big questions. If anything, it will only pose more difficult ones.