BY MISSY RYAN Reuters Almost as soon as Afghan insurgents began their assault on Western targets in Kabul on Sunday, US officials went to great lengths to stress that the bold offensive would do nothing to shake US strategy in Afghanistan. Yet alongside the reasons they stressed - the attacks' limited casualties, and the improving ability of Afghan forces to confront insurgents on their own - stands a fundamental reality: the Obama administration sees no palatable alternative to its current gradual course out of a war that has dragged on at great human and financial cost for over a decade. More than 10 years after the Taliban government was toppled following the Sept. 11 attacks in 2001, the US administration appears settled on a steady withdrawal of most of its troops by the end of 2014, leaving only a small US force to advise Afghan forces and conduct targeted strikes against militants. Top advisors to President Barack Obama, who is stepping up his campaign for a second term in November, have concluded that hard-won successes on the battlefield cannot alone guarantee a stable future for Afghanistan. At the same time, their bid to broker a peace deal with the Taliban has sputtered to a halt, at least for now. “These attacks don't affect our strategy because, again, they are not operational or strategic successes,” a US defense official said, speaking on condition of anonymity. “I don't think attacks like these - unless the Taliban can string together several actual successes - will impact the NATO/Lisbon timeline,” the official said, referring to the plan for NATO states to withdraw most of their troops by the end of 2014. Sunday's attacks appear certain to fuel doubts among many Afghans about whether their government, or the Taliban, will prevail when the West withdraws, undermining the “hearts-and-minds” element US commanders have said is central to the war. “Certainly this has a disproportionate propaganda effect for the insurgency,” said Jeffrey Dressler, a military expert at the Institute for the Study of War in Washington. But the violence is unlikely to alter significantly US strategy ahead of a NATO summit Obama will host in Chicago in mid-May. There, Obama and other NATO leaders are expected to define more clearly Western withdrawal plans - and for doing whatever they can to ensure Afghanistan does not collapse into civil war when foreign troops go home. NATO defense and foreign ministers are due to meet in Brussels to discuss the war and make final summit preparations on Wednesday and Thursday, but no sudden shifts are expected. “We've never really reacted to tactical events in a strategic way, and hopefully we don't start doing that now,” Dressler said. The attacks began in central Kabul in the early afternoon and rang out for hours as insurgents holed up in construction sites targeted NATO headquarters, the British and German embassies and the Afghan parliament building. A Taliban spokesman said it was the opening salvo of the insurgent group's spring offensive, and an act of revenge for a series of incidents involving US troops in Afghanistan - including the burning of Qur'ans at a NATO base and the massacre of 17 civilians by a US soldier. While Sunday's assault was larger than similar attacks last September, they do not appear to have caused major casualties. A series of apparently coordinated attacks also took place elsewhere in Afghanistan on Sunday. The Afghan Interior Minister said 19 insurgents, including suicide bombers, had died in attacks across the country. Fourteen police officers and nine civilians were wounded. Four insurgents were also detained in Kabul over a near-simultaneous assassination attempt on Afghan Vice President Karim Khalili, with Afghanistan's spy agency saying they belonged to the militant Haqqani network based in the Afghanistan-Pakistan border area. US officials say they had been bracing themselves for such attacks as the Taliban seeks to telegraph its resilience to Western offensives that NATO commanders say have weakened it. Under current plans, Obama plans to withdraw all of the 33,000 extra troops he sent to battle the Taliban in 2009-10 by around October, leaving about 68,000 US soldiers, most of whom would gradually head home in the year after that. The United States has vowed not to repeat the mistakes of the 1990s, when Afghanistan collapsed into civil war, and is expected to strike a deal with Kabul shortly that would authorize a modest US force to remain into 2015. Obama, who late last year ended the US military presence in Iraq, is also facing intense pressure to rein in spending at a time when support for the Afghan war has dropped, both among fellow Democrats and more traditionally hawkish Republicans. The success or failure of the Western effort in Afghanistan will hang largely on how well inexperienced, under-equipped Afghan forces will fare against the Taliban - meaning that Sunday's attacks provided a valuable glimpse of what lies ahead in Afghanistan as the Western presence narrows. US officials said it was too early to know whether Sunday's attacks were truly the work of the militants affiliated with the Haqqani network. Dressler said Haqqani authorship of the attacks would underscore the challenge NATO nations face in defeating an aggressive, highly trained branch of the Taliban active in areas of eastern Afghanistan that have not been the focus of Western fighting in the past. While NATO commanders are expected to intensify pressure on militants in some part of eastern Afghanistan, there will be no major influx of soldiers akin to the surge that pushed Taliban fighters out of many parts of southern Afghanistan in 2010. __