As long as former president, General Pervez Musharraf, was head of state, the Pakistani government was adamant that no international investigation into Benazir's death was necessary. Islamabad claimed to be sure that the leader of one of the Pakistani Taliban factions, Baitullah Mehsud, was culpable.

As a token, Musharraf allowed detectives from London's Scotland Yard to visit Pakistan to ascertain the modus operandi of Benazir's killing - that is, whether it was from the impact of a suicide bomb explosion that took at least 23 other lives on the spot or from a sniper's bullets. Even this technical detail has not be conclusively established to this day.

Musharraf's and the Pakistani military's bid to attribute Benazir's death to Mehsud did not convince the majority of Pakistanis, least of all the followers in her Pakistan People's Party (PPP). The gut instinct of almost every non-establishment observer during Musharraf's last months in power (he resigned on August 18, 2008) was that the notorious security and intelligence apparatus had had a hand in eliminating Bhutto, who was on a comeback trail after nearly a decade of formal military rule. When her widower, Asif Ali Zardari, came to power after an election in September 2008, it was therefore hoped that the PPP's demand for an impartial international inquiry into the assassination would begin immediately.

That the Zardari government took nine more months before the path was paved for the UN's troika of a Chilean, an Indonesian and an Irishman to commence the inquiry is reason to believe that they may be on a mission impossible. Although Musharraf now spends the evening of his career enjoying rounds of tennis and squash, his tribe of army generals and Inter-Services Intelligence (ISI) officers are very much in command behind the scenes. Unless there are serious rifts within the military-security complex, the UN's trio can be expected to be frustrated no end, just as the people of Pakistan have been for the past one-and-half years, irrespective of whether there was a general or a civilian in charge of the country.

The UN team's Irish member, Peter Fitzgerald, knows all about delaying tactics in assassination inquiries since he headed a UN fact-finding mission into the killing of former Lebanese prime minister Rafik Hariri in 2005 in Beirut. Syrian agents and pro-Syrian members of the Lebanese intelligence services, widely suspected of having had a hand in the murder, blocked all leads to conclusive evidence.

They forced Fitzgerald to report that no satisfactory international investigation was possible as long as Lebanon's security services remained under the leadership of that time. As predicted, the subsequent UN Independent Investigation Commission was left lamenting that Syria was not showing "greater and more meaningful cooperation" on the Hariri case.

Nearly four-and-half years have passed since Hariri's death by a probable suicide bomber, but the UN-assisted special tribunal for Lebanon has yet to indict anyone for the terrorist act which ushered in more instability in an already volatile country.

The team assigned to the Benazir assassination knows only too well from the Lebanese experience that high-political crimes are covered up in thick layers of deception, obstruction and burning up of traces of evidence. In a war-ridden and dangerously violent country such as Pakistan, the task is even more punishing. It is understandable that the UN team will operate outside the media glare so as not to raise the bar of expectations for the truth to pop out, clean and simple.

One special international diplomatic hurdle is also worth mentioning, although it will not be publicly mentioned by the UN investigating mission due to the delicacies of political correctness. Since the Pakistani army has launched an apparently more determined military offensive against the Pakistani Taliban in Swat Valley and, now, in Mehsud's lair of the South Waziristan tribal area, American policymakers have been all praise for this seemingly newfound zeal of the military and the ISI to take on the terrorist menace.

Easing their earlier reservations about the sincerity of Pakistan's security agencies to flush out and defeat the Taliban and al-Qaeda, everyone from US National Security Adviser General James Jones to US special envoy Richard Holbrooke has of late been back-patting the country's army. The increased "goodwill for Pakistan in the United States" could have an unexpected side-effect in the form of Washington enabling a downgrading of the UN's inquiry into Bhutto's assassination.

While the US cannot interfere with Fitzgerald and company to go slow or easy on the ISI and the Pakistani army's possible role in the killing, the idea that Pakistan's reluctant armed forces must be "encouraged" at a crucial time in the war on the Taliban takes many forms. Generous military and economic aid from Washington to Islamabad is an obvious publicized incentive, but the ability of Pakistan's generals to extract other types of concessions from the Americans is legendary. Will Bhutto's likely killers get off the hook due to backdoor American meddling? This factor cannot be underestimated, as the so-called "rogue elements" in the ISI and the army have long exploited American weaknesses.

Even in the UN's Hariri probe, there were well-founded hints that the US was willfully ignoring Syrian interference in the tribunal's progress as a quid pro quo for concessions on Middle East peace negotiations. The tribunal opened in The Hague this year exactly when the Barack Obama administration launched a flurry of diplomatic moves to bring Damascus out of the cold as a possible opening to resolve the Golan Heights dispute with Israel and to allegedly isolate Iran from its Arab allies.

Lebanese Druze leader Walid Jumblatt has already expressed angst that "the tribunal could be regarded as a bargaining chip with the Syrians". So, while Washington cannot directly pressurize a UN-supported tribunal based in The Hague, it can easily tolerate or wink at Syria's non-cooperation and allow Bashar al-Assad's government to keep the Hariri assassination a mystery forever.

The US bears a unique responsibility in aiding the UN to unearth the truth about Benazir's killing. It was on the assurances of both Musharraf and the George W Bush administration that political space would be created for Bhutto that she decided to return to Pakistan in 2007. As is the wont in any country rife with conspiracy theories, hearsay in Pakistan's streets is that the "Americans" and the army colluded to bump off "Bibi" (Benazir's affectionate name). Obama, a seeker of the truth in his own political context, should not allow a farcical finish to either the Hariri or the Benazir assassination cases.

Sreeram Chaulia is associate professor of world politics at the Jindal Global Law School in Sonipat, India.

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