U.S. President Barack Obama outlined a new strategy on Afghanistan in his address to the nation on Tuesday night, saying 30,000 troops would be additionally deployed by next summer.

After several months of consideration, Obama finally announced an Afghan troop buildup and pledged the United States would start withdrawing its troops in 18 months.

"As commander-in-chief, I have determined that it is in our vital national interest to send an additional 30,000 U.S. troops to Afghanistan," Obama told cadets in the West Point Military Academy, but noted that the new Afghan strategy would cost the country $30 billion for the first fiscal year.

In a speech the nation watched on television, Obama said the additional troops taken together would "allow us to accelerate handing over responsibility to Afghan forces, and allow us to begin the transfer of our forces out of Afghanistan in July of 2011."

"The 30,000 additional troops that I am announcing tonight will deploy in the first part of 2010 - the fastest pace possible - so that they can target the insurgency and secure key population centers," he said.

"They will increase our ability to train competent Afghan Security Forces... And they will help create the conditions for the United States to transfer responsibility to the Afghans," he said.