WASHINGTON, July 8 (Reuters) - President Joe Biden on Thursday strongly defended his decision to pull U.S. military forces out of Afghanistan, saying the Afghan people must decide their own future and that he would not consign another generation of Americans to the 20-year war. Speaking in the White House East Room, Biden said the Afghan military has the ability to repel the Taliban, denying reports that U.S. intelligence had forecast a collapse of the U.S.-backed government in Kabul in six months amid warnings of a civil war. Biden set a target date of Aug. 31 for the final withdrawal of U.S. forces, minus about 650 troops to provide security for the U.S. embassy in Kabul, and said thousands of Afghan interpreters will be moved to safety. A long-time skeptic of the 20-year military presence in Afghanistan, Biden said the United States had long ago achieved its original rationale for invading the country in 2001: to root out al-Qaeda militants and prevent another attack on the United States like the one launched on Sept.11, 2001. The mastermind of that attack, Osama bin Laden, was killed by a U.S. military team in neighboring Pakistan in 2011. Biden was careful not to declare victory, saying "there"s no mission accomplished." "We achieved those objectives, that"s why we went. We did not go to Afghanistan to nation build. And it"s the right and the responsibility of the Afghan people alone to decide their future and how they want to run their country," he said. According to an Ipsos poll from April, a majority of Americans support Biden"s decision to move troops out of Afghanistan, but only 28% of adults agreed that the U.S. accomplished its goals in Afghanistan, and 43% said the U.S. withdrawal now helps Al Qaeda. Addressing critics of his decision directly, Biden asked: "How many thousands more Americans, daughters and sons, were you willing to risk? How long would you have them stay?" "I will not send another generation of Americans to war in Afghanistan with no reasonable expectation of achieving a different outcome," he said. The speech represented Biden"s most extensive comments to date about the U.S. withdrawal from Afghanistan under pressure from critics to give more explanation for his decision to withdraw.Biden called on countries in the region to help bring about an elusive political settlement between the warring parties. He said the Afghan government should seek a deal with the Taliban to allow them to coexist peacefully. "The likelihood there"s going to be one unified government in Afghanistan controlling the whole country is highly unlikely," he said. Biden said the United States plans to move thousands of Afghan interpreters out of the country in August and they can safely apply for U.S. visas. Pentagon spokesman John Kirby said the United States was looking at a range of options to house Afghan interpreters temporarily as they wait for their visas, including potentially military installations on U.S. territory as well as in third countries. U.S. President Joe Biden delivers remarks on the administration"s continued drawdown efforts in Afghanistan in a speech from the East Room at the White House in Washington U.S., July 8, 2021. REUTERS/Evelyn Hockstein U.S. President Joe Biden delivers remarks on the administration"s continued drawdown efforts in Afghanistan in a speech from the East Room at the White House in Washington U.S., July 8, 2021. REUTERS/Evelyn Hockstein U.S. President Joe Biden delivers remarks on the administration"s continued drawdown efforts in Afghanistan in a speech from the East Room at the White House in Washington U.S., July 8, 2021. REUTERS/Evelyn Hockstein 1/3 U.S. President Joe Biden delivers remarks on the administration"s continued drawdown efforts in Afghanistan in a speech from the East Room at the White House in Washington U.S., July 8, 2021. REUTERS/Evelyn Hockstein Kirby said the administration was looking at how to move the interpreters from Afghanistan, but the preferred option was chartered commercial aircraft. The United States last weekend abandoned Bagram air base, the longtime staging ground for U.S. military operations in the country, effectively ending America"s longest war. read more The Pentagon says the withdrawal of U.S. forces is 90% complete. Washington agreed to withdraw in a deal negotiated last year under Biden"s Republican predecessor, Donald Trump. Biden overruled military leaders who wanted to keep a larger presence to assist Afghan security forces and prevent Afghanistan from becoming a staging ground for extremist groups. Taliban fighters seized control on Thursday of a district in western Afghanistan that includes a major border crossing with Iran, Afghan security officials said, as the Islamist insurgents continued their rapid military advances around the country. read more In the last week, the Taliban have overrun areas bordering five countries - Iran, Tajikistan, Turkmenistan, China and Pakistan. The commander of U.S. troops in Afghanistan, General Austin Miller, warned last week that the country may be headed toward a civil war. But Biden said Afghan troops far outnumber the Taliban, 300,000 to 75,000, and that a Taliban takeover can be stopped. "It"s not inevitable," he said. And he said there was no comparison between Taliban forces and the North Vietnamese Army that defeated the U.S.-backed South Vietnamese in the 1970s and prompted a hasty American withdrawal. "There"s going to be no circumstance you"re going to see people being lifted off the roof of an embassy in the -- of the United States from Afghanistan. It is not at all comparable," he said. U.S. Representative Michael McCaul, ranking Republican on the House Foreign Affairs Committee, said Biden had "only offered more empty promises and no detailed plan of action." "The time for platitudes and casting blame is over. The American people deserve answers and concrete solutions – not false hope," McCaul said. The U.S. intelligence community believes the Afghan military is weak and that the Kabul government"s prospects for survival in the short term are not good, U.S. government sources familiar with official assessments said. Biden denied that U.S. intelligence had forecast a collapse of the Kabul government in six months. Biden"s administration is also grappling with its plan for expedited visas for Afghan people most at risk of being attacked by the Taliban. Rights groups are pushing to add up to 2,000 vulnerable women to the list. read more