Afghan lawmakers said on Wednesday disaster and civil war would follow if Washington pushed ahead with a suggestion to withdraw all its troops from the country after 2014.
The White House said a day earlier it was considering the so-called "zero option" of a complete pullout - despite earlier recommendations from the top military commander in Afghanistan to keep soldiers there to help the government.
That option and the angry reaction from Afghan officials are likely to dominate talks between U.S. President Barack Obaba and his Afghan counterpart Hamid Karzai in Washington on Friday.
The meeting was already likely to be tense, given ongoing strains in their relationship over the war.
"If Americans pull out all of their troops without a plan, the civil war of the 1990s would repeat itself," said Naeem Lalai, an outspoken lawmaker from volatile Kandahar province, the birthplace of the Taliban.
"It (full withdrawal) will pave the way for the Taliban to take over militarily," Lalai told sources.
When the Soviets left Afghanistan in 1989 after a decade-long war, financial aid dried up and the Afghan communist government collapsed, leading to infighting between warlords. A civil war paved the way for the Taliban's rise to power.
The United States has about 68,000 troops there and that number was already expected to reduce sharply ahead of December 31 2014 - the official end of the NATO-led combat mission in the country.
NATO and its partners are racing against the clock to train up Afghanistan's 350,000-strong security forces though questions remain over how they well they will be able to tackle insurgents in the face of intensifying violence.
Many leading Afghan officials had assumed some U.S. troops would stay.
"If American forces leave Afghanistan without properly training the Afghan security forces, and equipping them, it would be a disaster," said influential member of parliament Mirwais Yasini.
Member of parliament Shukria Barekzai said a total withdrawal after 2014 would be equivalent to the United States "accepting defeat".
The Taliban said it was still considering whether to respond to the White House statement when contacted by the sources on Wednesday.
"It's very speculative and we are not commenting for now," said its spokesman Zabihullah Mujahid.
On Saturday the group reiterated its call for the immediate removal of all foreign troops from Afghanistan.
U.S. Deputy National Security Advisor Ben Rhodes said the complete withdrawal was "an option that we would consider" on Tuesday.
He made clear that a decision on post-2014 troop levels is not expected for months and will be made based on two U.S. security objectives in Afghanistan - denying a safe haven to al Qaeda and ensuring Afghan forces are trained and equipped so that they, and not foreign forces, can secure the nation.
Washington officials have privately said the White House is seeking a post-2014 presence of between 3,000 and 9,000 troops, which is significantly less than the 6,000 to 15,000 number given by the top commander, U.S. General John Allen.
© Thomson Reuters 2013