Afghan President Hamid Karzai Monday blamed intelligence failures, particularly on the part of NATO forces, for the biggest coordinated militant attacks on Kabul in 10 years of war.
Karzai's accusation came after an 18-hour assault by squads of Taliban, some disguised as women in burqas, on government offices, embassies and foreign bases in Kabul and neighbouring provinces. The attacks left 51 dead, including four civilians, 11 members of the security forces and 36 militants.
"The terrorists' infiltration in Kabul and other provinces is an intelligence failure for us and especially for NATO and should be seriously investigated," Karzai said in a statement.
Explosions and gunfire rocked the capital Sunday and overnight before Afghan forces regained control, heightening fears for the future of the vulnerable nation as NATO prepares to withdraw its 130,000 troops.
The Western alliance, which is committed to pulling out by the end of 2014 whatever happens militarily, put a positive spin on the attacks, hailing the performance of Afghan security forces.
Karzai also praised the rapid response by Afghan forces, saying it "proved to the people that they can defend their country successfully".
But his laying of the major share of the blame on troops whose home countries are already tired of the long war and its enormous cost is unlikely to go down well with his allies.
US Secretary of State Hillary Clinton said the United States, Pakistan and Afghanistan must take "robust action" to stop terror attacks.
Clinton discussed the attacks with Pakistani Foreign Minister Hina Rabbani Khar and "underscored our shared responsibility for robust action -- by the US and ISAF, by Afghanistan, and by Pakistan -- to confront and defeat terrorists and violent extremists," a US official said.
The United States said the attacks were likely carried out by Haqqani militants who operate from sanctuaries in Pakistan and dismissed Karzai's claim of an intelligence failure.
Defense Secretary Leon Panetta said the attacks were largely "symbolic" and praised the "great job" done by the Afghan security forces.
"There were no tactical gains here. These are isolated attacks that are done for symbolic purposes," Panetta told a news conference.
Martine van Bijlert of the Afghanistan Analysts' Network said: "That they did manage to pull off simultaneous complex attacks shows quite a level of sophistication in preventing detection... so that would be a failure in intelligence.
"But having said that, in a big bustling city like Kabul it is incredibly difficult to stop this type of attack."
UN Secretary General Ban Ki-moon condemned the attacks and noted the efforts of the Afghan security forces.
"It is ordinary Afghans who ultimately bear the brunt of such attacks," he said.
Afghan security forces took the lead in countering the insurgents, who were finally routed early Monday, but a spokesman for NATO forces said they had provided air support in response to requests from the Afghans.
"I am enormously proud of how quickly Afghan security forces responded to (the) attacks in Kabul," said General John Allen, commander of NATO's International Security Assistance Force.
ISAF labelled the attacks "largely ineffective". However, the fact that so many militants managed to make it through Kabul's so-called "Ring of Steel" checkpoints and attack high-value targets was a propaganda coup for the Taliban.
A Western diplomat with security expertise told AFP: "I don't share at all the optimism of NATO or the Americans.
"It's true that they did it better than in the past -- there is progress but still, to build up so many attacks and being able to launch them simultaneously demonstrates clearly (the Taliban's) ability to strike where and when they want," he said on condition of anonymity.
NATO insisted that the attacks would not influence its plans to withdraw.
"Clearly we still face security challenges," NATO spokeswoman Oana Lungescu told a news briefing in Brussels.
"But such attacks don't change the transition strategy," she said.
The British, German, Japanese and US embassy compounds came under fire as militants attacked the city's diplomatic enclave and tried to storm parliament, sparking a gun battle as lawmakers and bodyguards fired back from the rooftop.
The attacks marked the biggest assault on the capital in 10 years of war in terms of their spread and coordination, observers say.