In a tweet, Trump voiced continued skepticism about the extent of Russia’s cyber hacking. He and top advisers believe Democrats are trying to delegitimize his Nov. 8 election victory by accusing Russian authorities of helping him.

“The ‘Intelligence‘ briefing on so-called ‘Russian hacking’ was delayed until Friday, perhaps more time needed to build a case. Very strange!” Trump tweeted.

It was not clear when the briefing originally had been scheduled to take place. The White House did not immediately respond to a request for comment.

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Trump, who has cast doubt on U.S. intelligence agencies’ conclusion that Russia hacked Democratic Party computers, said over the weekend he would discuss the hacking allegations on Tuesday or Wednesday.

With his tweet, he suggested he would not address the subject until he had been briefed by intelligence officials.

Trump has scheduled a Jan. 11 news conference in New York. He is expected to discuss separating himself from his far-flung business empire, and other topics, including Russia, are likely to come up.

U.S. intelligence officials have said they are confident Russia was behind the hacks of political figures in an effort to help Trump win the presidential election.

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President Barack Obama retaliated to the hacking last week by ordering 35 Russian intelligence officials expelled from the United States and two Russian compounds shut down.

Trump told reporters on Saturday at his Palm Beach, Florida, resort that he knew “things that other people don’t know” about the hacking, “so we cannot be sure” who was responsible.

He said any computer was subject to hacks.

“It’s very important. If you have something really important write it out and have it delivered by courier the old fashioned way,” Trump said, adding: “No computer is safe, I don’t care what they say.”