NATO chief backs Obama's threat to Karzai, says alliance will pull out of Afghanistan without BSA

BRUSSELS -- NATO's secretary general says that if Afghan leaders and the White House can't agree on a key security pact, the U.S.-led alliance will pull all of its troops and equipment out of Afghanistan by December.

The blunt statement from Anders Fogh Rasmussen Wednesday at the start of a NATO defense ministers meeting ratchets up pressure on Afghan President Hamid Karzai to strike a deal.

On Tuesday, President Obama threatened to withdraw all U.S. troops from Afghanistan by the end of this year if the Bilateral Security Agreement (BSA) isn't signed.

CBS News correspondent David Martin reported that while the threat of the so-called "zero option" -- a complete withdrawal -- had been on the table for some time, and the Pentagon has been working on contingency plans for it, Tuesday's phone call was the first time Karzai had heard it directly from Mr. Obama. 

"We will leave open the possibility of concluding a BSA with Afghanistan later this year," the White House said in a summary of the call between the two leaders. However, the White House added that "the longer we go without a BSA, the more likely it will be that any post-2014 U.S. mission will be smaller in scale and ambition."

Martin said the U.S. currently has about 34,000 troops in Afghanistan, and the top American commander in the country has suggested keeping around 10,000 there after the bulk come home this year -- but only if the U.S. and Afghan governments can agree to and sign a BSA.

Without that agreement, Rasmussen said, forces from other NATO countries and partners cannot stay beyond 2014 either. There are roughly 19,000 non-U.S. forces now in Afghanistan.

"Let me stress, this is not our preferred option," Rasmussen said. "But these are the facts." The NATO chief was to hold meetings with other defense chiefs, including his U.S. counterpart Chuck Hagel, during this week's meetings in Brussels, and Afghanistan was expected to be a primary topic of discussion.

Many Afghan leaders and security officials have expressed serious concern about the readiness of the nation's police and soldiers to stand up to the Taliban and other insurgent groups without Western backup.

On Tuesday, speaking to CBS News on the condition of anonymity, a senior government official from neighboring Pakistan put it starkly, saying the "zero option should not be an option. It means civil war in Afghanistan."

The official said Afghan security forces were simply not ready for the fight on their own, and cautioned that many -- as much as 30 percent of the overall Afghan security force -- could simply walk off the job and return to their villages if the U.S. troops pulled out entirely.

He also worried that without foreign military backup, bloodshed in Afghanistan would increase and spill over the border in the form of more attacks on Pakistan. Afghanistan's leaders have for years pointed the finger, in turn, at Islamabad, saying many of the attacks on Afghan and NATO troops are carried out by militants who have bases on the Pakistani side of the nations’ shared border.

The official noted that Pakistan was already home to "millions" of Afghan refugees, and said any new influx sparked by a deterioration in the already-tenuous security situation in the neighboring nation would be a disaster for Pakistan's government.