A retired Air Force general who served as a senior military advisor to Trump just endorsed Biden for president

• Nearly 500 former national security leaders signed an open letter backing Democratic nominee Joe Biden for president.
• Among the signatories was retired Air Force Gen. Paul Selva, who served as the vice chairman of the Joint Chiefs of Staff during the first two and a half years of the Trump administration.
• The letter published Thursday follows a letter signed by more than 200 military leaders supporting President Donald Trump as he seeks re-election.

Retired Air Force Gen. Paul Selva, who advised President Donald Trump as a member of the Joint Chiefs of Staff, is among nearly 500 former national security leaders who endorsed Democratic nominee Joe Biden for president in an open letter Thursday.

Selva, a four-star general who served during the Obama administration, was re-nominated by Trump to serve as the vice chairman of the Joint Chiefs of Staff, a group of senior uniformed leaders who advise the president. He retired last summer.

As the second highest-ranking military officer, he had a front-row seat to major crises, such as tensions with North Korea that nearly ignited a war.

While retired Marine Corps Gen. Joseph Dunford, who served as the top general and the chairman of the Joint Chiefs of Staff, has chosen to stay out of politics, and refusing to comment on the president, Selva has publicly endorsed Trump's political opponent.

In an "Open Letter to America," 489 former national security leaders, to include 22 four-star generals, backed Biden over Trump.

"The next president will inherit a nation – and a world – in turmoil," the letter reads. "The current President has demonstrated he is not equal to the enormous responsibilities of his office; he cannot rise to meet challenges large or small."

"Joe Biden has the character, principles, wisdom, and leadership necessary to address a world on fire," the letter concludes.

The letter published Thursday by "National Security Leaders for Biden" comes on the heels of an open letter signed by 235 retired senior military officers backing Trump's re-election.

That letter, which was signed by eight former four-star generals, states that the signers "believe that President Donald Trump is committed to a strong America" and that as president, "he will continue to secure our borders, defeat our adversaries, and restore law and order domestically."

While the active-duty military strives to remain apolitical, it is not uncommon for retired military leaders to publicly endorse a presidential candidate.