WASHINGTON - U.S. Secretary of State Antony Blinken, testifying at a congressional hearing Monday, is staunchly defending the country's military withdrawal last month from Afghanistan that ended a two-decade war, the longest in U.S. history.

Had U.S. President Joe Biden decided to keep armed forces in Afghanistan, it "would have required sending substantially more U.S. forces into Afghanistan to defend ourselves and prevent a Taliban takeover, taking casualties - and with at best the prospect of restoring a stalemate and remaining stuck in Afghanistan, under fire, indefinitely," Blinken told the House Foreign Affairs Committee.

"There's no evidence that staying longer would have made the Afghan security forces or the Afghan government any more resilient or self-sustaining," he said. "If 20 years and hundreds of billions of dollars in support, equipment, and training did not suffice, why would another year, or five, or 10, make a difference?"

Taliban insurgents took over the country in mid-August as Afghan President Ashraf Ghani fled to exile in the United Arab Emirates. The U.S. evacuated 124,000 people, most of them Afghans, along with about 5,500 Americans, from the Kabul airport in the last days of August, leaving behind about 100 Americans.

Some Americans have subsequently been able to leave the country, through overland exits or on a handful of flights, with the Taliban's acquiescence.

Blinken said U.S. officials did not foresee the downfall of the Afghan government so quickly, even as the Taliban advanced throughout the country.

"Even the most pessimistic assessments did not predict that government forces in Kabul would collapse while U.S. forces remained," he said.

Even though the main evacuation has ended, the top U.S. diplomat said, "We're continuing our relentless efforts to help any remaining Americans, as well as Afghans and citizens of allied and partner nations, leave Afghanistan if they choose."

"As we've done throughout our history, Americans are now welcoming families from Afghanistan into our communities and helping them resettle as they start their new lives," Blinken said. "That's something to be proud of, too."

Blinken is likely to face tough questioning before the House panel, and again Tuesday when he appears before the Senate Foreign Relations Committee.

Opposition Republican lawmakers and some Democratic colleagues of Biden have criticized the president's handling of the withdrawal of troops, American citizens and thousands of Afghans who worked for U.S. forces as interpreters and advisers during the war.

The criticism was especially pronounced after 13 U.S. service members died in a suicide bomb attack at the Kabul airport in the waning days of the withdrawal. Islamic State-Khorasan, an Afghan offshoot of the terrorist group operating in the Middle East, claimed responsibility.

National polls of U.S. voters show wide support for Biden's decision to end what he has called a "forever war" in Afghanistan, but not the way the withdrawal unfolded.

Blinken is likely to be asked why the U.S. did not start evacuating American citizens sooner, especially since Biden announced his intention in April to honor former President Donald Trump's agreement with the Taliban to end the war and withdraw American forces.

Lawmakers have also taken aim at U.S. intelligence-gathering for failing to forecast the rapid takeover by the Taliban and the collapse of the Afghan government.

Republicans say they want to focus their questioning on Biden's performance in the final weeks and days of the war, while Democrats are hoping to examine the whole of the American war effort that was conducted under four presidents - Republicans George W. Bush and Trump, and Democrats Barack Obama and Biden.

Bush launched the war in late 2001 to eradicate al-Qaida terrorist training grounds where the September 11, 2001 terrorist attacks against the U.S. were spawned. Nearly 3,000 people were killed in the attacks that used hijacked U.S. passenger airliners. The 20th anniversary of the attacks was commemorated last Saturday.

Biden has called the withdrawal an "extraordinary success" and defended the decision to end the war in Afghanistan, saying he would not pass on responsibility for managing U.S. military involvement there to a fifth U.S. leader.