Fifty prominent Republican national security officials, including a former CIA director, on Monday (August 8) called party nominee Donald Trump unqualified to lead the country and said he would be "the most reckless president in American history."

The statement was the latest repudiation of Trump's candidacy by veteran Republican national security specialists, and was remarkable for the harshness of its language.

"Mr. Trump lacks the character, values, and experience to be president. He weakens U.S. moral authority as the leader of the free world. He appears to lack basic knowledge about and belief in the U.S. Constitution, U.S. laws and U.S. institutions, including religious tolerance, freedom of the press, and an independent judiciary," the statement said.

"None of us will vote for Donald Trump," said the statement, which noted that some signatories also have doubts about Democratic presidential nominee Hillary Clinton.

The statement did not cite specific comments by Trump, but it clearly was a response to a series of remarks he has made questioning the need for NATO, expressing admiration for Russian President Vladimir Putin, calling for a temporary ban on immigration by Muslims, and inviting Russia to hack Clinton's private email server - which he later said was a joke.

The signatories, some of whom worked for more than one Republican president, included former Central Intelligence Agency Director Michael Hayden, who also headed the National Security Agency; former Homeland Security Secretary Michael Chertoff; former Director of National Intelligence John Negroponte; and two former U.S. trade representatives, Carla Hills and Robert Zoelick.

Other signatories included former senior State Department, Pentagon and National Security Council officials who helped plan and oversee the 2003 U.S. invasion of Iraq. Trump has harshly criticized the Iraq operation, although when radio host Howard Stern asked him in 2002 if he favored invading Iraq, Trump said he guessed he did.

The statement was organized by Philip Zelikow, who served as a top adviser to former Secretary of State Condoleezza Rice.

Trump responded with a statement deriding the signatories as members of "the failed Washington elite" who "deserve the blame for making the world such a dangerous place."

"These insiders - along with Hillary Clinton - are the owners of the disastrous decisions to invade Iraq, allow Americans to die in Benghazi, and they are the ones who allowed the rise of ISIS," he continued, using an acronym for the Islamic State militant group.