Afghan withdrawal best decision for US: Biden

United States President Joe Biden said withdrawing the troops from Afghanistan to end the 20-year war was the "best" and the "right" decision for America.

He said there was no reason to continue in a war that was no longer in the service of the "vital national interest" of the American people.

"I give you my word: With all of my heart, I believe this is the right decision, a wise decision, and the best decision for America," Biden said in his address to the nation from the White House on Tuesday.

"We've been a nation too long at war. If you're 20 years old today, you have never known an America at peace. So, when I hear that we could've, should've continued the so-called low-grade effort in Afghanistan, at low risk to our service members, at low cost, I don't think enough people understand how much we have asked of the 1 percent of this country who put that uniform on, who are willing to put their lives on the line in defense of our nation," he said.

Telling his fellow Americans that the war in Afghanistan is now over, Biden said he is the fourth President who has faced the issue of whether and when to end this war.

"When I was running for President, I made a commitment to the American people that I would end this war. And today, I've honoured that commitment. It was time to be honest with the American people again. We no longer had a clear purpose in an open-ended mission in Afghanistan," he said.

"After 20 years of war in Afghanistan, I refused to send another generation of America's sons and daughters to fight a war that should have ended long ago," Biden added.

After more than US$ 2 trillion spent in Afghanistan -- a cost that researchers at Brown University estimated would be over US$ 300 million a day for 20 years in Afghanistan -- for two decades, he said.

"If you take the number of US$ 1 trillion, as many say, that's still US$ 150 million a day for two decades. And what have we lost as a consequence in terms of opportunities? I refused to continue in a war that was no longer in the service of the vital national interest of our people," he added.

"As Commander-in-Chief, I firmly believe the best path to guard our safety and our security lies in a tough, unforgiving, targeted, precise strategy that goes after terror where it is today, not where it was two decades ago. That's what's in our national interest," the President said.

Biden said that the world is changing and the US is confronted with new challenges.

"We're engaged in a serious competition with China. We're dealing with the challenges on multiple fronts with Russia. We're confronted with cyberattacks and nuclear proliferation," he said.

"We have to shore up America's competitive(ness) to meet these new challenges in the competition for the 21st century. And we can do both: fight terrorism and take on new threats that are here now and will continue to be here in the future," he added.

Biden said, "There's nothing China or Russia would rather have, would want more in this competition than the United States to be bogged down another decade in Afghanistan. As we turn the page on the foreign policy that has guided our nation the last two decades, we've got to learn from our mistakes."

He said the terror threat has spread across the world, well beyond Afghanistan.

"We face threats from al-Shabaab in Somalia; al Qaeda affiliates in Syria and the Arabian Peninsula; and ISIS attempting to create a caliphate in Syria and Iraq, and establishing affiliates across Africa and Asia," he added.

"The fundamental obligation of a President, in my opinion, is to defend and protect America -- not against threats of 2001, but against the threats of 2021 and tomorrow. That is the guiding principle behind my decisions about Afghanistan. I simply do not believe that the safety and security of America is enhanced by continuing to deploy thousands of American troops and spending billions of dollars a year in Afghanistan," Biden said.

"But I also know that the threat from terrorism continues in its pernicious and evil nature. But it's changed, expanded to other countries. Our strategy has to change too," he added.

The United States, he said, will maintain the fight against terrorism in Afghanistan and other countries.

"We just don't need to fight a ground war to do it. We have what's called over-the-horizon capabilities, which means we can strike terrorists and targets without American boots on the ground -- or very few, if needed," he said.

"We've shown that capacity just in the last week. We struck ISIS-K remotely, days after they murdered 13 of our servicemembers and dozens of innocent Afghans. And to ISIS-K: We are not done with you yet," Biden said.