PHILADELPHIA — There was plenty of news to discuss on the third morning of the Democratic convention at the Wells Fargo Arena here in Philadelphia. There was Bill Clinton's speech on behalf of his wife. A controversy over Hillary and TPP. The Democrats' continued downplaying of terrorism as a threat facing America.

It was all in the daily mix — until about 11:00 a.m., when Donald Trump walked to a microphone for a news conference at Doral, his resort in Miami.

Trump made news right and left. Questioned about fallout from the DNC email hack, he denied any ties to Russia. He said he would be "firm" with Vladimir Putin, but he wanted Russia's cooperation in the fight against ISIS and other international matters. He attacked Hillary Clinton over her own email scandal, suggesting the Russians might well have broken in to her system.

And then Trump said: "Russia, if you're listening, I hope you're able to find the 30,000 [Clinton] emails that are missing.'

It was an extraordinary moment. Whatever one's reaction to what he said, the fact is that in one brief appearance, Trump dominated the news cycle at a time when coverage is supposed to belong to the party holding its convention.

There used to be an informal agreement among presidential campaigns that a candidate would mostly "go dark" during his opponents' convention. It wasn't a matter of courtesy as much as recognition that it would be very hard for an opponent to break through the wall of news coverage devoted to the convention.

Donald Trump has demolished that conventional convention strategy.

"Trump has blown up that precedent and inserted himself on an hourly basis into the news cycle during Hillary Clinton's convention," said Ryan Williams, an aide to Mitt Romney in 2012, in a phone conversation. "I think that's a good idea for [Trump]. Why cede any ground at this point in the race? The Trump campaign has successfully utilized free media for the last year and a half to drive his campaign message. Why stop now?"

In addition to coverage of the Democratic convention, Clinton is also running tens of millions of dollars in ads in key states. Trump is not. Grabbing attention — wresting control of the debate — is key for Trump to stay in front of voters' eyes.

And by answering reporters' questions about Russia and bringing up the Clinton email scandal on his own, Trump once again directed attention to one of Clinton's greatest liabilities at precisely the moment she didn't want it discussed.

Another reason Trump intervened is because he can. In 2012 and 2008, Mitt Romney and John McCain gave mostly conventional stump speeches most of the time. They could talk boilerplate all they wanted during their opponents' conventions and not attract much coverage. Trump, on the other hand, says something controversial or outrageous or entertaining nearly every time he appears before a microphone. That's what he did Wednesday.

Even though in the past candidates stayed fairly quiet, the campaigns did try to shape coverage during conventions. This week, for example, Republicans have a big operation in Philadelphia. They've been featuring surrogate speakers and pushing rapid response, like noting that Democrats have said virtually nothing about ISIS in the convention so far. But the RNC can't grab the spotlight by the throat the way Trump can.

Is that good or bad? Many Democratic strategists believe Trump gives them new talking points every time he opens his mouth. Whether that benefits them or not, they realize Trump is playing a new sort of game.

"Modern communications technology has shortened the news cycle and created an avalanche of new information," said former Democratic Rep. Dennis Kucinich, who ran for president himself in 2004 and 2008. "This necessarily affects political parties, changes communications strategy, and invites the kind of counter-messaging that's coming from the Trump campaign."

So Trump's is perhaps the first truly 21st-century campaign?

"Au courant," Kucinich answered. "He gets it."