WASHINGTON -- Republican presidential nominee Donald Trump has suggested Russia should hack the e-mails of his Democratic opponent, Hillary Clinton, eliciting widespread disbelief and fueling further fears about the prospect of a foreign government meddling in the U.S. election.



Speaking one day after Democratic convention delegates formally chose Clinton to be their candidate, Trump also said that, if elected, he would reconsider U.S. sanctions against Russia for its annexation of Ukraine's Crimean Peninsula in 2014.



Clinton’s campaign responded to Trump's remarks about her e-mails, accusing him of encouraging Russia to spy on the United States and meddle in U.S. politics.



"I will tell you this: Russia, if you're listening, I hope you’re able to find the 30,000 e-mails that are missing," Trump told reporters during the televised news conference. "I think you will probably be rewarded mightily by our press. Let's see if that happens."

While Trump treated the matter rather flippantly, saying that he saw no problem if Russia or China hack U.S. political e-mails and leak them, his vice-presidential running mate, Mike Pence, said it was a "serious" matter and he expected the FBI to get to the bottom of it.

"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," Pence said.

Clinton's chief foreign-policy adviser, Jake Sullivan, said Trump's invitation to Russia "has to be the first time that a major presidential candidate has actively encouraged a foreign power to conduct espionage against his political opponent."



"This has gone from being a matter of curiosity, and a matter of politics, to being a national security issue," Sullivan said.

Clinton has been under fire for months after a congressional investigation discovered that she had been using a private e-mail server to handle classified and unclassified correspondence while serving as secretary of state. She later apologized for the decision.

The "30,000" figure mentioned by Trump refers to the correspondence that Clinton said she deleted from the private server because she considered them personal.

'Extremely Careless'



The FBI has investigated whether Clinton or her aides broke any laws concerning the handling of classified secrets. Last month, the bureau's director announced that no criminal charges would be filed, but also excoriated her as being "extremely careless."

Trump's comments come in the wake of a massive leak of e-mail correspondence among party officials, released on the eve of the convention, that Democrats have suggested were caused by hackers with links to the Russian state.



The e-mails, which derided Clinton's Democratic opponent, Bernie Sanders, sparked outrage among Sanders' supporters. The party's chairwoman stepped aside after they were published by Wikileaks on July 22.



The e-mails released so far only deal with Democratic party deliberations; there is no indication that any came from Clinton’s private e-mail server.



Attention has shifted in recent days to the source of the leak, with U.S. intelligence officials and private security researchers saying it was likely orchestrated by the Russian intelligence agencies.



The Democratic Party first reported last month that its servers had been breached. The alleged cyberattack that resulted in the leaked e-mails is being investigated by the FBI.



Trump suggested that there would be nothing wrong with Russia or another foreign power gaining access to the e-mails and revealing their content.



"No, it gives me no pause," the celebrity businessman said. "If Russia or China or any of those country gets those e-mails, I've got to be honest with you, I'd love to see them."



The four-day Democratic convention got off to a rocky start on July 25 when the chairwoman was forced to step aside following a massive leak of e-mail correspondence among party officials, released on the eve of the convention.



The e-mails, which derided Clinton's Democratic opponent, Bernie Sanders, sparked outrage among Sanders' supporters.Those released so far only deal with Democratic Party deliberations; there is no indication any came from Clinton's private e-mail server.

Smoking Gun?



Attention has shifted in recent days to the source of the leak, with U.S. intelligence officials and private security researchers saying it was likely orchestrated by the Russian intelligence agencies.



The hack, which was first reported by the Democratic Party last month, is being investigated by the FBI.



In a widely discussed analysis published on the legal blog Lawfare, a former lawyer for the National Security Agency said the publicly available evidence appeared to back that up.



"Paired with the technical indicators, the sum total of evidence is about as close to a smoking gun as can be expected where a sophisticated nation state is involved," the lawyer, Susan Hennessey, wrote in the post published July 25.

In an interview with NBC News July 27, President Barack Obama suggested that Russian meddling in the U.S. election was a possibility.



"What we do know is that the Russians hack our systems, not just government systems but private systems," he said.



"What the motives were in terms of the leaks, I can't say directly," he said, but "anything is possible.”

Kremlin spokesman Dmitry Peskov on July 27 denied the allegations, telling reporters that U.S. politicians were "paranoid."



"President Putin has repeatedly said that Russia has never interfered and does not interfere in internal affairs, especially in the electoral processes of other countries," Peskov said.



Trump, who has made positive comments about Putin during the campaign, said on July 27 that Putin "has much better leadership qualities than Obama."

He has openly called for mending relations with Moscow, which have sunk to Cold War lows over Ukraine, Syria, and other issues.



During the news conference, Trump was also asked whether, if elected, he would recognize Crimea as Russian territory and lift U.S. sanctions imposed on Russia over its annexation of the Black Sea peninsula -- home to a strategic Russian naval base -- from Ukraine in 2014.

"We'll be looking at that," Trump responded.



The Kremlin has pushed hard, in Washington and other Western capitals, to lift the sanctions, which helped push Russia's economy into recession last year, and have severely crimped growth this year.