The top U.S. military commander in Afghanistan has welcomed President Barack Obama's approval of 17,000 additional troops to Afghanistan, saying the development will markedly improve deteriorating security conditions in the southern part of the country.

Army General David McKiernan says 2009 will be a "tough year" for U.S. troops in Afghanistan. But, he says, that with the addition of two combat brigades during the next several months, he expects the security situation to improve.

"We do see with these additional forces as an opportunity to break this stalemate, at least in terms of security conditions in the south," said General McKiernan. "So I look forward to the arrival of these capabilities and to further contributions and commitment by the international community."

McKiernan says that while the insurgency by the Taliban and other militant groups in the south and along the Afghanistan-Pakistan border is not growing, it is resilient.

In addition to putting more troops at outposts along the border, where insurgents have been able to move freely, McKiernan says U.S. forces will help develop Afghan police and army counterinsurgency efforts.

"What we want to get to is what I've called the 'tipping point,' where the lead for security is in Afghan units - police and army - and we increasingly are in a more mentoring and training role," he said.

McKiernan says that for the next three to five years, the United States will need to remain heavily committed in Afghanistan. But he says, it is in the international community's vital interest to provide the country with stability.

"The insurgency is not going to win in Afghanistan," saiod McKiernan. "The vast majority of the people who live in Afghanistan reject the Taliban or other militant insurgent groups. They have nothing to offer them; they do not bring any hope for a better future. The insurgency will not win in Afghanistan."

The general had initially requested 30,000 troops. But he says, the additional 17,000 troops will be enough to last through August, when Afghan elections are expected to take place.