WASHINGTON - The "zero option" in Afghanistan - a complete pullout of U.S. troops - is unrealistic and there will need to be some level of U.S. involvement in the country even after the 2014 withdrawal, a Pentagon official said today.

Peter Lavoy, the Pentagon's top policy official on Afghanistan, said today the agency has developed a number of plans for U.S. involvement after the 2014 withdrawal based on the current situation on the ground, which was highlighted in a new six-month review of the security situation in Afghanistan.

The report addresses the effect US and NATO troops pulling back from patrolling and giving most of that responsibility to Afghan forces has had.

Lavoy said that though the transition remains on track, some troops and funding will need to remain in order to support Afghan security forces training, advising and for counterterrorism efforts.

He did not give a recommendation for a specific number troops or funding amount that will be needed, but did call the "zero option," where the United States would pull out completely, unrealistic.

"In none of these cases have we developed an option that is zero," Lavoy said.

The report shows that U.S. and NATO casualties are at their lowest since 2008. But shows the price that Afghan security forces are paying is very high at several hundred fatalities a month. The report outlines, for the first time, how high their fatality numbers have spiked.

For example In January 2012 Afghan security force fatalities were around 70 to 80. They jumped up to 280 in July 2010 and dipped again during the winter lull. But they went sky-high beginning in January peaking at around 330 in March of this year.

The report makes the point that enemy initiated attacks aren't a good indicator of security in Afghanistan given that most occur in areas where only 20 percent of the population lives. Also, nationwide enemy-initiated attacks are more difficult to compile given that U.S. troops are no longer where they used to be. It also says a better indicator is the number of Afghan troops now being fielded, which is near the cap of 352,000 established for them.

"The insurgency is now less capable, less popular and less of an existential threat to GIROA (Afghanistan) than in 2011," the report says the Taliban is resorting to high profile attacks in key Pashtun areas.

But interestingly the report says that the Taliban is now focusing on "non-kinetic means of influencing the local population." For example, Taliban leadership ordered guidance to avoid Afghan civilian casualties. This new Taliban focus has led to an increase in the number of ceasefires between Taliban forces and Afghan security forces.

There has been a reduction in the number of insider attacks, where Afghan security forces attack their American counterparts, this year. The vast majority of civilian casualties are caused by the Taliban; coalition caused civilian casualties decreased by 60 percent, while insurgent cause civilian casualties increased by two percent.

Corruption is another threat to the stability of the country, Lavoy said, calling it a "critical concern." He said that while some of what is viewed in America as corrupt practices, such as influence peddling, are socially accepted in Afghanistan, there is clearly a problem with blatant corruption that is undermining progress.

"There's clearly abusive corruption, very corrosive, toxic corruption that's taking place. And it is a priority," said Lavoy who added that the Pentagon believes dealing with corruption is a top priority for the Afghan government.

"Secretary Hagel's counterparts are the minister of defense and the minister of interior. And in their conversations and other DOD officials with these individuals, they've identified anti-corruption as a priority for them," he said.