The people who planned and executed the 9/11 attack are still operating in the area and plotting attack against the United States, the White House today said, adding this is the reason why America continues to be in Afghanistan.

"We should keep in mind that the reason we are in Afghanistan is because the people who plotted and executed the attacks on 9/11 are still operating there and are plotting attacks against Americans even now," White House Deputy Press Secretary Bill Burton told reporters abroad Air Force One traveling with US President Barack Obama [Images], en route to Andrews Air Force Base from Mexico.

President Obama, he said, feels that the troops in Afghanistan are operated under some of the most dangerous conditions in the world and they are doing it bravely and with a great amount of courage. Obama fully supports what the US troops are doing in Afghanistan, he said.

The new Af-Pak strategy announced in March this year is still to be fully implemented, he said, adding that the aim of the new strategy is to ensure the defeat of Taliban [Images] and al-Qaeda.

Observing that the US is in a very tough situation in Afghanistan, Burton said the White House believes that there is a strategy in place.

Noting that there would be no change in the strategy, he said: "The President authorised 21,000 new troops for Afghanistan -- they're not all on the ground just yet, but we believe that with the strategy and the assets and the infusion of resources, that we're going to be able to achieve our goals."

When asked if there would be any increase in the number of US troops in Afghanistan, he said the commander of the US forces is currently reviewing the situation and would come out with his own set of recommendations.

"The President's strategy hasn't fully been implemented just yet. But we do believe that with the strategy that we have, with assets that we're putting on the ground, that we are going to be able to achieve the goals that we're trying to achieve," he said.

"President is in close contact with his commanders on the ground, but again, thinks that the strategy that he put in place is a winning one," Burton said.