House Republicans ramp up investigation into Afghanistan withdrawal

The House Foreign Affairs Committee has served Secretary of State Antony Blinken with a subpoena for a classified document from diplomats in Kabul warning the Afghan government was at risk of collapse as the last American troops prepared to exit.

It marks a significant escalation in the GOP probe of how the Biden administration handled the tumultuous U.S. withdrawal.

The Republican chairman of the committee, Rep. Mike McCaul, said in a statement Monday night that the panel "made multiple good faith attempts to find common ground" with Blinken to allow lawmakers to see what's called a "dissent cable" sent to State Department leadership in July 2021 as well as Blinken's reply, calling the communication "a critical piece of information."

"Unfortunately, Secretary Blinken has refused to provide the dissent cable and his response to the cable, forcing me to issue my first subpoena as chairman of the committee," McCaul continued, adding that the panel expects the State Department will "follow the law and comply with this subpoena in good faith."

But State Department officials have indicated that the agency is unlikely to hand over the documents without mounting a challenge.

"The department followed up with the committee to reiterate its willingness to provide a briefing about the concerns raised and the challenges identified by Embassy Kabul, including in the dissent channel. The Committee chose instead to issue a subpoena," State Department Principal Deputy Spokesperson Vedant Patel said in statement.

"The department remains committed to providing the committee the information it needs to conduct its oversight function, and has already provided thousands of pages of documents responsive to the committee's request," Patel said.

Blinken argued against supplying lawmakers with the requested documents during a hearing before the committee last week, claiming that turning them over may have a chilling effect on State Department employees who are free to use the private channel within the department to express misgivings or concerns.

"The tradition of having a dissent channel goes back decades," the secretary testified. "It's a unique way for anyone is the department to speak truth to power as they see it without fear or favor. And they do it by the regulations we established for these cables in a privileged and confidential way."

But Republicans and even some Democrats say that there is value in examining the documents, which provide a first-hand account of conditions on the ground in Afghanistan during the days and weeks leading up the final, chaotic phase of the U.S. withdrawal as a Taliban offensive swept across the country and threatened the capital.

A source previously told ABC News that the cable, co-signed by nearly two dozen U.S. Embassy staffers on July 13, 2021, called on the Biden administration to begin airlifting Afghan allies out of the country immediately and urged Washington to use stronger language to condemn the Taliban's atrocities.

The source said Blinken promptly read the cable and responded to it. The Biden administration also announced an operation to relocate Afghans who worked with U.S. and NATO forces the day after the initial memo was sent.

However, evacuations did not begin until late July, meaning only a small share of the tens of thousands of Afghans eligible for special immigration visas could be taken out before Kabul was retaken by the Taliban, prompting bipartisan criticism of the Biden administration.

In the hectic final days of the U.S. occupation, the terrorist group ISIS-K also carried out a suicide bombing near the crowded entrance to the Hamid Karzai Intenational Airport in Kabul, killing 13 American servicemembers and scores of Afghans.

"The American people deserve answers as to how this tragedy unfolded," McCaul said in his statement announcing the subpoena.

ABC's Cindy Smith and Conor Finnegan contributed to this report.