More than 200 former development officials with the U.S. Agency for International Development signed a letter released Tuesday in support of their State Department colleagues who have been called to testify before House investigators handling the impeachment inquiry of President Trump.

“Together, we spent our careers working to represent the policies and values of the United States,” the letter said. “We are angered at the treatment of dedicated, experienced, and wise public servants like Ambassador Marie Yovanovitch; and we are distraught at the dangers inherent in the President’s cavalier (and quite possibly corrupt) approach to making foreign policy on impulse and personal interest rather than in response to national security concerns.”

The statement became public as another former State Department official was scheduled to testify behind closed doors Tuesday in the House impeachment inquiry. William B. Taylor Jr. , a retired civil servant who headed the U.S. Embassy in Kyiv after the administration abruptly recalled Yovanovitch, said in a text that he considered it “crazy” to withhold U.S. military aid to Ukraine unless Kyiv agreed to investigate former vice president Joe Biden — Trump’s political rival — and his son Hunter Biden.

Terry Myers, a retired Russia desk officer for USAID when Taylor was coordinating aid to countries that broke away from the Soviet Union, said many of the letter’s signatories knew and worked with Taylor, Yovanovitch and other former officials who have been called to testify.

“Bill Taylor has been the coordinator of foreign assistance to the former Soviet Union, Iran, Afghanistan and the Middle East,” he said. “He’s everybody’s favorite go-to coordinator of interagency foreign assistance. These are people we’ve admired and worked with for years.”

USAID is an independent arm of the State Department, responsible for coordinating most of the humanitarian and development aid the United States spends every year. Like Foreign Service officers for the State Department, its officials serve in many hardscrabble and dangerous places, working together with the diplomats.

Myers said the letter began circulating around midday Monday and had more than 200 signatories by the next morning, with more rolling in by the hour. They include people who worked in the Washington offices, as well as overseas, as career Foreign Service officers, civil servants and political appointees. Myers said all are retired, although a few have returned to work at USAID temporarily on a contract basis.

But the rapidity with which the former officials rushed to add their names to the list signified the depths of their alarm about what they have witnessed not only in recent weeks but in the almost three years of the Trump administration.

The letter said the retired officials were “appalled” that foreign aid was used to leverage political objectives.

“The way the President is conducting foreign policy raises questions about the reliability of the U.S. as a partner, its commitment to diplomatic norms, and its capacity for leadership,” it says. “His administration’s treatment of State Department officers raises concerns about whether we will have the human and institutional capacity to answer those questions.”

The letter also said Trump’s foreign policy and treatment of nonpartisan employees is negatively affecting U.S. relationships with its allies and is the root of a surge of resignations and a plunge in recruitment.

“If there is one small consolation all of us can take from recent events in Ukraine, it is that the country has been introduced to public servants like Ambassadors Marie Yovanovitch, Michael McKinley, William Taylor and DAS George Kent,” the letter said. “They represent the high integrity, capability and professionalism of career State Department officers, and we are proud to stand with them.”

McKinley is a former senior adviser to Secretary of State Mike Pompeo; Kent is a deputy assistant secretary of state. Both have testified in the inquiry.

The American Academy of Diplomacy also put out a statement of support for the diplomats on Tuesday, noting they took an oath to defend the Constitution and protect the interests of the United States.

“Happily, most who take this oath never face the choice of following the law or following a contradictory order from their leaders,” the statement said. “That was no longer true for some of our former colleagues. They met their responsibilities by honoring subpoenas to appear before the Congress even when reportedly told not to do so by the State Department. We admire their bravery and courage.”

And 36 former diplomats who served in embassies and consulates around the world sent a separate letter to Pompeo on Tuesday, calling on him to publicly renounce all political retaliation against State Department employees, “whatever its source.” They also urged him to renounce his previously stated objections to diplomats complying with subpoenas to testify to House investigators.