300+ former national security officials condemn Trump-Ukraine actions

What they're saying: "The revelations of recent days, however, demand a response. Specifically, all of us recognize the imperative of formal impeachment proceedings to ascertain additional facts and weigh the consequences of what we have learned and what may yet still emerge. We applaud those Members of Congress, including Speaker Pelosi, who have no started us down the necessary path."

• The letter is signed by former officials who worked under both Democratic and Republican administrations.

That list includes:

• William Burns — Former Deputy Secretary of State
• Nancy McEldowney — Former U.S. ambassador
• Jeffrey Feltman — Former Assistant Secretary of State for Near Eastern Affairs

Worth noting: The letter was put together by National Security Action, which mostly consists of of national security officials from the Obama administration. They often release statements similar to this one about the Trump administration.

Go deeper: The call heard 'round the world