The assassination on Tuesday of the Afghan government’s chief peace negotiator Burhanuddin Rabbani is another significant setback to the efforts of the US and its client regime in Kabul to reach a political settlement with the Taliban.

Rabbani was killed in his Kabul home by a suicide bomber who set off explosives concealed in his turban. The attacker, named Esmatullah, claimed to be an emissary from the Taliban and insisted that he had to speak directly to Rabbani, who flew back from Dubai specifically to hold the meeting.

Afghan President Hamid Karzai established the country’s High Peace Council, which Rabbani headed, last year to conduct talks with the Taliban. However, the talks have been sporadic and inconclusive. Desperate for a breakthrough, Karzai phoned Rabbani and urged him to return to meet Esmatullah, who claimed to have an important message from the Taliban leadership based in Quetta, Pakistan.

Speaking to Reuters, a Taliban spokesman claimed responsibility for the assassination, but the Taliban later issued an online denial. Who ordered the killing is not clear, but US and Afghan officials variously pointed the finger at the Taliban, the allied Haqqani network based in North Waziristan and the Pakistani military intelligence agency—the Inter-Services Intelligence (ISI).

The ability of anti-occupation militias to penetrate the heavy security surrounding top Afghan government figures again points to the presence of high-level Taliban sympathisers within the Afghan state bureaucracy, military and police.

A former aide to Rabbani, Amanullah Paiman, told the Washington Post: “I am sure that without inside and outside help this incident would not have happened. This man was kept in the [High Peace Council] guesthouse for a week and nobody paid attention to his movement, turban and acts.”

Rabbini’s death follows other high-profile assassinations, including the killing of President Karzai’s half-brother Ahmed Wali Karzai in Kandahar on July 12 and of top presidential adviser Mohammed Jan Khan in Kabul on July 17. Last week, Taliban gunmen were able to enter a partially completed, high-rise building in the heavily guarded diplomatic sector of Kabul and attack the US embassy and NATO headquarters with guns and rockets for 24 hours.

Rabbani was regarded by the Karzai regime as a key figure in the peace talks. He was an Islamist cleric who led one of the CIA-funded Mujaheddin militias that fought against the Soviet-backed regime in Kabul in the 1980s. After the withdrawal of Soviet troops, Rabbani became the president in 1992 and continued to hold the post even after bloody fighting broke out between the feuding ruling factions. Rabbani, like his rivals, was responsible for terrible war crimes. He was driven out of Kabul in 1996 by the Taliban, backed by the Pakistani ISI, with the tacit approval of Washington.

As an ethnic Tajik warlord, Rabbani was regarded as useful in ensuring that Tajik parties backed the negotiations with the Taliban, which is based on the country’s ethnic Pashtun majority. His assassination will only exacerbate ethnic tensions and undermine the Karzai regime, which came to power with the backing of the US and the Northern Alliance of Tajik, Uzbek and Hazara organisations.

Tajik leaders aligned with Rabbani have sharply criticised Karzai and the peace talks. Abdullah Abdullah, Karzai’s rival in the last presidential election, told the Washington Post that the efforts to get the Taliban to lay down their arms and join the government were naive. Referring to Rabbani’s killers, he said: “These are the people President Karzai calls ‘dear brothers’... the ones who have killed thousands of people.”

Amrullah Saleh, former head of the Afghan intelligence agency, told the Wall Street Journal: “The Taliban have killed... national figures and President Karzai calls them his brothers and calls Pakistan a friendly nation. The government doesn’t know who is the enemy and who is the friend.” Karzai forced Saleh to resign earlier this year after he opposed negotiations with the Taliban.

It is not simply Karzai that has pushed the peace talks, however. The “surge” strategy pursued by the Obama administration was aimed at boosting US troop numbers and military operations against the Taliban to force them to the negotiating table and allow security to be handed over to the Karzai regime by 2014.

Mid-level American officials from the State Department and CIA have met with Taliban officials on at least three occasions in Qatar and Germany. The Taliban, however, has refused to talk about a political settlement until all foreign troops have left Afghanistan. As a result, fighting has only intensified, with the US carrying out its own war of assassination against alleged “terrorist” leaders in Afghanistan and Pakistan, using special forces troops and drone strikes.

Following Rabbani’s assassination, Obama repeated what has become the standard line in response to escalating high-profile attacks—it will not affect the “transition.” But the new US ambassador to Kabul, Ryan Crocker, told the Wall Street Journal on September 8: “The Taliban need to feel more pain before you get a real readiness to reconcile.” In other words, the war will escalate further and become even more brutal.

At the same time, the US is ramping up its pressure on the Pakistan government and military to crack down on the Haqqani network, which it accuses of being responsible for the attacks in Kabul. On Tuesday, the same day Rabbani was killed, US Defence Secretary Leon Panetta told a press conference that Pakistan had to take stronger action against insurgents entering Afghanistan.

“We cannot have Haqqanis coming across the border attacking our troops and [Afghans] and disappearing back into a safe haven. That is not tolerable, we have urged them to take steps,” Panetta said. He went on to warn that the United States would “take whatever steps are necessary to protect our forces.”

A decade after the US invaded Afghanistan, there is no end in sight to its bloody war, which seeks to transform the country into a base of operations in the neighbouring energy-rich regions of the Middle East and Central Asia. As American imperialism sinks further into the quagmire, it is also profoundly destabilising Pakistan as the US military attempts to suppress the intensifying armed opposition to the US-led occupation.