Why US Troops Are Staying Longer in Afghanistan

— -- The announcement that thousands of U.S. troops will remain in Afghanistan longer than planned marks a major reversal of President Obama's goal to end both this war, as well as the war in Iraq, during his time in office.

Recent upheavals in the region and a renewed show of strength by the Taliban were some of the major factors playing into the decision.

The president formally announced the policy change at the White House this morning alongside Vice President Joe Biden, Secretary of Defense Ash Carter and Chairman of the Joint Chiefs of Staff Joseph Dunford.

Why Do the Troops Have to Stay?

The decision comes as the situation in Afghanistan continues to deteriorate, highlighted by the Taliban’s takeover of the city of Kunduz last month. Afghanistan’s President Ashraf Ghani is more receptive to keeping U.S. troops in Afghanistan than former President Hamid Karzai.

The United Nations says the Taliban are now in more parts of Afghanistan than any time since their ouster.

ISIS has also gathered steam and recruits in the country, and al Qaeda elements still find safe haven in the Afghan mountains.

The decision came after a months-long comprehensive review that began in the spring and included conversations among Obama, Afghan President Ghani and Chief Executive Officer Abdullah Abdullah.

Senior administration officials said the United States will continue to maintain two non-combat missions in Afghanistan -- a counter-terrorism mission to "go after Al Qaeda, deal with terrorist threats," and a training, advising and assisting mission for Afghan forces. Those are the same missions U.S. troops are carrying out today.

How Many Will Remain in Afghanistan?

Obama said the United States will keep its 9,800 troops in Afghanistan through most of 2016, until the drawdown begins.

By the end of 2016, that number will decrease to 5,500 troops, but officials would not provide a timeframe for that decrease, saying it would be a decision that will come in consultation with commanders on the ground and allies.

The 5,500 troops will be stationed in Jalalabad, Kandahar, Kabul and Bagram.

How Does This Differ From the Original Plan?

Today's announcement marks a stark contrast to the government's former plan.

Officials had said that they planned to keep only about 1,000 troops on the ground by the end of 2016, with their main task being embassy security and working in a new security cooperation office.

How Much Will This Cost?

Several factors were considered as the president's advisers crafted a plan, including cost implications and an analysis of risks to both the missions and the force. The officials said the president deeply wanted to ensure that forces would be adequately protected.

The cost estimate for this new plan is $14.6 billion for 2017, compared to the $10 billion originally planned for the Kabul-centric presence.