Scenes around Hamid Karzai International Airport in Kabul on Tuesday showed Taliban fighters appearing to wear Afghan National Army uniforms after the militant group took control of the airport following the U.S. military's full withdrawal from the country -- a far different picture from the days preceding.

Resources left behind in the wake of mass evacuations, including equipment stamped with American and Afghan national flags, littered the area where U.S. troops recently stood guard. Taliban fighters have apparently since seized some equipment distributed to the Afghan army by the U.S. before it collapsed.

As the 20-year war came to a close on Monday, the Pentagon said that the cost, in human lives, was 2,461 troops killed and more than 20,000 injured.

Since the evacuation mission began, 6,000 citizens and more than 123,000 people -- Afghan "friends and allies" -- were flown out of Afghanistan by the U.S. and partners, but 100 to 200 American citizens still wanting to leave remain, officials said, as well as thousands of Afghans who worked with the U.S. and fear reprisal from the Taliban,

GOP Rep. Michael McCaul, R-Texas, said Republicans had sent letters to the Department of Defense, the Department of State and the intelligence community asking agencies to preserve documents relating to the Afghanistan withdrawal for what they said would be a future investigation.

"We want the Democrats to join us but we are going to do it with or without, exercising our constitutional authority of oversight to get to the bottom of how this got so wrong," McCaul, the top Republican on the House Foreign Affairs Committee said at a news conference on Capitol Hill Tuesday.

The announcement comes after House Minority Leader Kevin McCarthy said Friday there would be "a day of reckoning" for Biden, promising an investigation into the withdrawal. Other GOP House members criticized Biden's withdrawal, with Rep. Mike Rogers, R-Mich., saying "this disaster is solely the responsibility" of Biden, Secretary of State Anthony Blinken and national security adviser Jake Sullivan.

Vice President Kamala Harris gaveled in a pro forma session of the Senate on Tuesday morning, to enable the passage of a bill that will help with the repatriation of Americans coming from Afghanistan, according to a White House aide.

The bill provides emergency, temporary assistance for Americans returning from Afghanistan. It was passed without any objection at roughly 10:30 a.m. and will now head to the president’s desk since it originated in and already passed the House.

Secretary of State Antony Blinken said on Monday there is still a "small number of Americans -- under 200, and likely closer to 100 -- who remain in Afghanistan and want to leave."

-ABC News’ Trish Turner and Sarah Kolinovsky

Taliban spokesperson Zabihullah Mujahid told Taliban soldiers at a press conference hours after the last U.S. soldiers left the airport in Kabul that they had secured victory for the whole of the Afghan nation.

"Due to the sincerity, perseverance, and patience of our elders, we gained our freedom. I congratulate all of you and our nation on this freedom, and I hope that Afghanistan will never be occupied and that it will be free, prosperous, and the home of Afghans, and that there will be an Islamic government," he said, according to a translation of his remarks from Reuters.

Mujahid said the Taliban wanted to sustain good relations with the rest of the world, that Afghanistan was not a country for occupying forces, and that Americans were defeated and could not achieve their goals.

"The nation has suffered a lot, and they have been repressed because of the occupation, have seen problems for 20 years, and can no longer tolerate misbehavior. Therefore, I call on all our militaries to treat the people well because the people have the right to peace, to unite, and we are the servants of the nation, not to dominate the people," he said.

-ABC News' Aleem Agha and Guy Davies