Trump Concedes Russia Was Behind Hacking, Says Putin 'Shouldn't Have Done It'

— -- President-elect Donald Trump said today he accepts the intelligence community’s conclusion that Russia was behind the massive alleged hacking of political organizations and individuals during the U.S. presidential race — the first time he has conceded that Russia was behind the cyberattacks.

"As far as hacking, I think it was Russia," Trump told reporters during his first press conference since winning the Nov. 8 election. "But I also think we've been hacked by other countries, other people."

Trump added that Russian President Vladimir Putin "shouldn't have done it" and he doesn't believe Putin will "be doing it more now" after he's inaugurated on Jan. 20.

Last week Trump and President Barack Obama were separately briefed on a classified intelligence report on Russia's alleged interference in the 2016 presidential election. A declassified version was released afterward that said Putin ordered a campaign to influence the contest between Trump and Democratic candidate Hillary Clinton.

"We assess Russian President Vladimir Putin ordered an influence campaign in 2016 aimed at the U.S. presidential election. Russia's goals were to undermine public faith in the U.S. democratic process, denigrate Secretary Clinton and harm her electability and potential presidency," the report reads, citing the Russian government's "long-standing desire to undermine the U.S.-led liberal democratic order."

"We further assess Putin and the Russian government developed a clear preference for President-elect Trump," the report continues, saying Putin nursed a "grudge" against Clinton "for comments he almost certainly saw as disparaging."

After being briefed on the report, Trump took to Twitter to blame the Democratic National Committee's "gross negligence" in the cyberattacks.

At the press conference Trump said it would be "very important" to develop a "hacking defense" because "the United States is hacked by everybody."

When asked by ABC News' Jonathan Karl whether he accepted that the Russian president ordered the influence campaign in favor of a Trump victory, Trump continued to assert that the United States will benefit from a stronger relationship with Moscow.

"We have a horrible relationship with Russia," he responded. "If Putin likes Donald Trump — guess what, folks — that’s called an asset, not a liability."

Trump said the Russian government will have "far greater respect" for the United States with him at the helm, adding that he will be "tougher" on Putin than Clinton would have been.

"Now, I don't know that I'm going to get along with Vladimir Putin. I hope I do. But there's a good chance I won't," he said. "And if I don't, do you honestly believe that Hillary would be tougher on Putin than me? Does anyone in this room really believe that? Give me a break."

ABC News' Malka Abramoff, Paul Blake and Meghan Keneally contributed to this report.