Defense Secretary Lloyd Austin and Chairman of the Joint Chiefs of Staff Gen. Mark Milley should resign following the “disastrous” withdrawal from Afghanistan, a group of 87 retired generals said in an open letter on Monday.

The letter, from a group called “Flag Officers 4 America,” said Austin and Milley showed “negligence in performing their duties” for the swift exit from Afghanistan, which has left Americans and Afghan allies stranded and “de facto hostages of the Taliban,” Business Insider reported Tuesday.

The group said Austin and Milley should have recommended against the quick exit, and should have resigned in protest if they weren’t able to convince President Joe Biden otherwise.

“A fundamental principle in the military is holding those in charge responsible and accountable for their actions or inactions,” the retired generals said in the letter. “There must be accountability at all levels for this tragic and avoidable debacle.

“Conversely, if they did do everything within their ability to persuade the CINC/President to not hastily exit the country without ensuring the safety of our citizens and Afghans loyal to America, then they should have resigned in protest as a matter of conscience and public statement.”

Gen. Kenneth F. McKenzie, head of U.S. Central Command, said Monday that more than 122,000 civilians from Afghanistan had been evacuated since the end of July, Business Insider reported.

However, dozens of Americans and thousands of Afghan allies had not been able to leave.

Milley has spoken about the lack of intelligence, indicating Afghanistan would fall to the Taliban as fast as it did.

“Flag Officers 4 America,” which describes itself as “retired U.S. generals and admirals defending the Constitution,” previously wrote an open letter in May. That letter questioned the results of the 2020 election, as well as Biden’s physical and mental health.

The generals’ letter Monday said the “consequences” of “this disaster are enormous,” and include the “death and torture of Afghans” and “indescribable” damage to America’s reputation, Business Insider said.

The letter also said it was “catastrophic” to have advanced military equipment falling into the hands of America’s enemies.

USA Today reported Monday that tens of millions of dollars of aircraft, armored vehicles, and sophisticated defense systems likely were left behind, some of which were rendered inoperable before leaving. McKenzie said the U.S. had permanently disabled more than 150 vehicles and aircraft before leaving Kabul.

“Flag Officers 4 America” also claimed that “due to the weakness displayed in Afghanistan,” adversaries such as China and Russia would be “emboldened to move against America” and that terrorists would “pass freely into our country” via the U.S.-Mexico border.