"We have cut off their head and we will ultimately defeat them," Obama said in his address to the US soldiers after meeting privately with the full assault team that killed the al-Qaida leader.
"We''re making progress in our major goal, our central goal in Pakistan and Afghanistan, and that is disrupting and dismantling -- and we are going to ultimately defeat al Qaeda," Obama said in his first major address on this issue after he announced on Monday that Osama has been killed in a successful US operation in Abbottabad, Pakistan.
"Across Afghanistan, we've broken the Taliban's momentum. In key regions, we've seized the momentum, pushing them out of their strongholds. We're building the capacity of Afghans, partnering with communities and police and security forces, which are growing stronger," he said at Fort Campbell, Kentucky.
Obama said the US-led international forces have put al Qaeda's leadership under more pressure than at any time since 9/11, on both sides of the border.
"So the bottom line is this: Our strategy is working, and there's no greater evidence of that than justice finally being delivered to Osama bin Laden," he asserted.
At the same time, Obama conceded that this continues to be a very tough fight.
"You know that. But because of this progress, we're moving into a new phase. In the coming months, we'll start transferring responsibility for security to Afghan forces.
Starting this summer, "we'll begin reducing American forces. As we transition, we'll build a long-term partnership with the Afghan people, so that al Qaeda can never again threaten America from that country," he said.