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Republican presidential nominee Donald Trump’s comments that Russia should "find the 30,000 emails that are missing" from Hillary Clinton's email account provoked outrage from national security experts across the spectrum on Wednesday.

Some of the strongest condemnation came from the former director of the National Security Agency and the CIA under George W. Bush.

Trump dropped his latest bomb early Wednesday following widespread speculation that Russia was behind the hack of Democratic National Committee emails.

The candidate said at a press conference in Florida: "Russia, if you're listening, I hope you're able to find the 30,000 emails that are missing. I think you will probably be rewarded mightily by our press. Let's see if that happens."

"Perhaps he doesn't know what he's talking about. Just a theory"

Following Trump's comments, Republican House Speaker Paul Ryan offered tepid damnation, focusing on the foreign threat rather than his party's figurehead:

"Russia is a global menace led by a devious thug," Ryan said. "Putin should stay out of this election."

Meanwhile, retired U.S. Air Force general Michael Hayden, director of the NSA and CIA under president George W. Bush, criticized Trump’s comments in an interview with Bloomberg View columnist Eli Lake.

"If he is talking about the State Department e-mails on her server, he is inviting a foreign intelligence service to steal sensitive American government information," Hayden said. "If he is talking about the allegedly private e-mails that she destroyed, he is inviting a foreign intelligence service to violate the privacy of an individual protected by the Fourth Amendment to the American Constitution."

"Perhaps he doesn't know what he's talking about. Just a theory," Hayden said.

Related: Trump's Russian Hacker Plea Roils Campaign

Other prominent Republicans brushed off Trump's explosive comments as misunderstood.

Supporters Rudy Giuliani, the former New York City mayor, and former House Speaker Newt Gingrich were among them. Gingrich called the comments "a joke," while Giuliani said, "I'm sure what he means is that they should be released to the FBI. I'm sure that's what he means."

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The media seems more upset by Trump's joke about Russian hacking than by the fact that Hillary's personal server was vulnerable to Russia — Newt Gingrich (@newtgingrich) July 27, 2016

Trump later said on Twitter that if Russia or any other country has any of Clinton's emails, they should turn them over to the FBI.

Related: FBI Recommends No Criminal Charges Against Hillary Clinton

Trump’s running mate, Indiana Gov. Mike Pence, said in a statement released while Trump was speaking that warned of "consequences” if Russia was found to be interfering with the election.

"The FBI will get to the bottom of who is behind the hacking," the statement said. "If it is Russia and they are interfering in our elections, I can assure you both parties and the United States government will ensure there are serious consequences."

A Pence aide said the statement was drafted before Trump’s speech Wednesday. The aide said Pence takes the same position as Trump, that if Russia has any of the missing emails they should release them.

Related: Why Experts Are Sure Russia Hacked DNC Emails

Former U.S. ambassador to Russia Mike McFaul, who served under President Barack Obama, said he was taken aback by Trump’s comments.

"I just find it deeply troubling that any American, let alone one running for president of the United States, would encourage Russian espionage. That's just, is unprecedented to me," McFaul told NBC News.

The U.S. relationship with Russia is a tense one. Obama imposed sanctions on Russia following the annexation of Crimea in 2014. Russian military aircraft and naval vessels have been accused of conducting dangerous stunts near the Baltic Sea and in the Mediterranean Sea.

Trump last week suggested the U.S. would not necessarily defend new NATO members in the Baltics in the event of Russian attack if he were elected to the White House. The comments to the New York Times set off alarm bells in Europe.

Retired U.S. admiral and former supreme commander of NATO James Stavridis on Wednesday called Trump’s comments "dangerous at every level — as international cyber policy, as domestic political tactic, and as an approach to the conduct of foreign affairs."

Putin has praised Trump before. The Russian leader on Friday called Trump “bright” and said he appreciates his openness to engage Russia, according to The Associated Press.

And in an appearance on MSNBC back in December, Trump said, "When people call you brilliant, it's always good, especially when the person heads up Russia."

Trump has also called Putin's praise "a great honor."

At Wednesday’s press conference, Trump took a different tone, saying Putin has over the past year has said "some really bad things" and that Putin "mentioned the n-word one time." Trump made those comments in arguing that Putin does not respect Obama, and promising that he would be better respected by Putin if elected president.

Andrew S. Weiss, former director for Russian, Ukrainian, and Eurasian Affairs on the National Security Council staff and a policy assistant in the Office of the Under Secretary of Defense for Policy during the administrations of Presidents Bill Clinton and George H. W. Bush, called Trump’s comments “a seismic development.”

"There is a persistent pattern of very flamboyant comments about Russia and Mr. Putin in particular dating back the beginning of the [Trump] campaign," he said. "Today’s comments about email hacking and the Clinton server fit squarely into that pattern, and fly in the face of years of Republican orthodoxy and mainstream thinking about Russia."

"I'm surprised that an issue that is now being looking at extremely closely by law enforcement and national security officials is being played for laughs given the stakes and the very real question of whether Russian government agencies are trying to influence the course of a U.S. presidential election," Weiss said. "That’s a seismic development any way you approach it."

Presidential historian and NBC News analyst Michael Beschloss said Trump's comments were out of line with tradition in American presidential elections.

"The tradition has usually been that American presidential candidates have told other countries to stay out of our elections," said Beschloss, author of numerous books on presidential crises. "And traditionally Americans resent it when another country has tried to get involved."

"I just find it deeply troubling that any American, let alone one running for president of the United States, would encourage Russian espionage"

While the circumstances and order of magnitude in this case may be extraordinary, there have been examples, some cited in Beschloss' books, of Russians or their Soviet predecessors offering help to preferred presidential candidates.

In one case, during the 1960 presidential campaign, a Soviet diplomat approached a member of John F. Kennedy's inner circle and asked if there anything they could do or say that would help Kennedy defeat Vice President Richard M. Nixon. The response, according to the historical accounts was, do not meddle, the fear being if the Russian help became known, it would be devastating. The communications ended.

Trump, who fondly recalls when America was "great," could literally have been locked up in 1950s for saying what he said about Russia today. — John Harwood (@JohnJHarwood) July 27, 2016

Two presidential terms later, the Soviets declined an offer to convene a U.S.-U.S.S.R. summit late in the 1968 campaign that might have helped vice president Hubert Humphrey in his campaign against Nixon.

The agenda would have included the Vietnam War, the most divisive issue in a particularly divisive campaign. After Nixon, then seen as more of pragmatist, was elected, a Soviet diplomat reminded Nixon that if they had agreed to the summit, it would have hurt him.

McFaul, the former ambassador, said there is no doubt Putin's government wants Trump to win the White House.

"Oh they love this, of course they love this, they think this is going to be great," McFaul said. "There's no question that President Putin and his government have made very clear that they would prefer to deal with Donald Trump as opposed to Secretary Clinton, because he supports their policies."

"When I was in the government dealing with top Russian officials, they respect strength, they respect people that push back and defend American national interest," McFaul said. "When you say 'I think Russia should do espionage against us' — that's not a statement of strength."