Donald Trump asked Russia to hack into rival Hillary Clinton’s emails Wednesday, publicly inviting a foreign nation to spy on a former U.S. government official and meddle in an American election.

The Republican presidential nominee made the audacious ask during a press conference at his resort in Doral, Fla.

“Russia, if you’re listening, I hope you’re able to find the 30,000 emails that are missing,” Trump said. “I think you will probably be rewarded mightily by our press.”

Clinton’s team was quick to respond. “This has to be the first time that a major presidential candidate has actively encouraged a foreign power to conduct espionage against his political opponent,” said Clinton’s chief foreign policy adviser Jake Sullivan. “This has gone from being a matter of curiosity, and a matter of politics, to being a national security issue.”

Trump himself has referenced the missing emails — which Clinton’s team admitted to deleting from her servers due to their “personal and private” nature — as a national security issue throughout his campaign. After a lengthy investigation, FBI Director James Comey found Clinton and her team to be “extremely careless” in using a private server but recommended to the Department of Justice that “no charges” be filed against them. Clinton admitted in a recent “60 Minutes” interview that she “made a mistake” and pledged no private email servers would be used if she were elected president.

Trump’s running mate Mike Pence released a statement following Trump’s press conference warning any interference. “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,” the Indiana governor wrote.

Russian intelligence agencies are widely believed to be behind last week’s hacking of the Democratic National Committee’s servers, where 20,000 emails were stolen and later released by WikiLeaks. The emails revealed that several DNC members favored Clinton over her primary rival Bernie Sanders, a revelation that angered many of Sanders’ supporters and led to protests at this week’s national convention.

Russia has denied any involvement in the hack. “President (Vladimir) Putin repeatedly said that Russia never interfered into internal affairs of other countries, especially in electoral processes,” Kremlin spokesman Dmitry Peskov told reporters Wednesday. “Moscow scrupulously avoids any actions, any statements that could be interpreted as direct or indirect interference into electoral processes.”

Trump reiterated his request in a tweet following his press conference.

If Russia or any other country or person has Hillary Clinton's 33,000 illegally deleted emails, perhaps they should share them with the FBI! — Donald J. Trump (@realDonaldTrump) July 27, 2016

Clinton has not directly responded to Trump’s request. The Democratic presidential nominee is expected to take the stage at the Democratic National Convention on Thursday in Philadelphia.