WASHINGTON, Aug 16 (Reuters) - U.S. President Joe Biden on Monday stood by his decision to end the longest war in United States history and rejected criticism from both allies and adversaries that poor planning led to the chaotic scenes at the Kabul airport following the collapse of the Afghanistan government to the Taliban. Biden, speaking from the East Room in the White House, conceded that the rise of Taliban forces and the deterioration of Afghanistan"s military happened much more rapidly than he had expected but insisted there was never a good time to withdraw U.S. forces. Here are a few excerpts from his speech: "I stand squarely behind my decision. After 20 years, I"ve learned the hard way that there was never a good time to withdraw U.S. forces." "I always promised the American people that I will be straight with you. The truth is: This did unfold more quickly than we had anticipated. So what"s happened? Afghanistan political leaders gave up and fled the country. The Afghan military collapsed, sometimes without trying to fight." "So I"m left again to ask of those who argue that we should stay: How many more generations of America"s daughters and sons would you have me send to fight Afghans - Afghanistan"s civil war when Afghan troops will not? How many more lives - American lives - is it worth? How many endless rows of headstones at Arlington National Cemetery?" "I made a commitment to the brave men and women who serve this nation that I wasn"t going to ask them to continue to risk their lives in a military action that should have ended long ago. Our leaders did that in Vietnam when I got here as a young man. I will not do it in Afghanistan." "I know my decision will be criticized, but I would rather take all that criticism than pass this decision on to another President of the United States - yet another one - a fifth one." "As we carry out this departure, we have made it clear to the Taliban: If they attack our personnel or disrupt our operation, the U.S. presence will be swift and the response will be swift and forceful. We will defend our people with devastating force if necessary." "The events we"re seeing now are sadly proof that no amount of military force would ever deliver a stable, united, secure Afghanistan, that is known in history as the graveyard of empires. What"s happening now, could just as easily happened five years ago, or 15 years in the future." "Now we are focused on what is possible. We will continue to support the Afghan people. We will lead with our diplomacy, our international influence, and humanitarian aid ... We will continue to speak out for the basic rights of Afghan people, for women and girls – just as we speak out all over the world.” Reporting by Steve Holland and Jarrett Renshaw; Editing by Karishma Singh Our Standards: The Thomson Reuters Trust Principles.