FILE - Sen. John McCain, R-Ariz., (left) and Sen. Lindsey Graham, R-S.C., wait to speak during a news conference on Capitol Hill in Washington, Jan. 21, 2016.
FILE - Sen. John McCain, R-Ariz., (left) and Sen. Lindsey Graham, R-S.C., wait to speak during a news conference on Capitol Hill in Washington, Jan. 21, 2016.

The U.S. Senate Armed Services Committee is to hold a briefing Thursday for members to learn more about the Obama administration's response to suspected Russian interference in the 2016 election and harassment of American diplomats.

Committee chairman Senator John McCain on Wednesday called the Russian interference "an act of war." U.S. intelligence officials, including national intelligence director James Clapper, are expected to testify.

"If you try to destroy the fundamentals of democracy, then you have destroyed a nation," McCain told reporters on Capitol Hill. "And by the way, there are various gradients of acts of war. I'm not saying it's an atomic attack. I'm just saying that when you attack a nation's fundamental structure, which they are doing, then it's an act of war."

New Congress
Vice President Joe Biden administers the Senate oath of office to Sen. John McCain, R-Ariz., accompanied by his wife, Cindy McCain, and his family during a a mock swearing-in ceremony in the Old Senate Chamber on Capitol Hill in Washington, Jan. 3, 2017.

President Barack Obama hit back at Moscow last week with a set of sanctions targeting Russia's leading spy agencies, which the U.S. has accused of meddling in the presidential campaign. The administration also kicked out 35 Russian diplomats in response to what it said has been Russia's harassment of American envoys.

Trump’s skepticism

Two days before he will receive a highly anticipated intelligence briefing, President-elect Donald Trump continued Wednesday to question the view that Russia meddled in the presidential election by hacking confidential information and leaking it selectively before Americans voted. In a series of tweets starting late Tuesday, Trump taunted the CIA, FBI and other agencies, suggesting they still don't have proof that Russia penetrated Democratic party computers and gave the documents to WikiLeaks.

"The 'Intelligence' briefing on so-called 'Russian hacking' was delayed until Friday, perhaps more time needed to build a case. Very strange!" Trump said.

And then early Wednesday, after WikiLeaks founder Julian Assange appeared on Fox News denying the Russian government gave WikiLeaks stolen Democratic documents, Trump followed up: "Julian Assange said 'a 14-year-old could have hacked Podesta' - why was DNC so careless?"

Trump was referring to thousands of emails and documents that hackers took from the computers of the Democratic National Committee and from Hillary Clinton campaign chief John Podesta, which were published by WikiLeaks in the weeks leading up to the November 8 presidential election.

Some of the documents were embarrassing to the Clinton campaign, and analysts say they likely contributed to Trump's victory over the former secretary of state.

The Central Intelligence Agency and the Federal Bureau of Investigation have both concluded that the Russian government was behind the hacking, and intentionally divulged the documents via WikiLeaks to disrupt the election.

Demonstrators make their way around downtown, Mond
FILE - Demonstrators make their way around downtown, Monday, July 25, 2016, in Philadelphia, during the first day of the Democratic National Convention after some of the 19,000 emails, presumably stolen from the DNC by hackers, were posted to the website WikiLeaks.

Another U.S. Senate committee, Foreign Relations, will hold a closed-door meeting on the same issue.

Hacking report

 U.S. intelligence chiefs and Obama have pointed the finger at Russian President Vladimir Putin, saying no such operation could go on in Moscow without the highest level of approval.

Republican Senator Lindsey Graham, a Trump critic, sharply questioned the president-elect's reliance on Assange.

"I don't believe any American should give a whole lot of credibility to anything Julian Assange says," Graham said on Twitter. Later, he added, "Assange has a record of undermining the United States."

A U.S. official confirmed to VOA on Wednesday that the intelligence community's review of potential foreign interference in the U.S. elections is now complete. The official also said Obama will be briefed about the matter Thursday, one day before Trump will receive the same briefing.

Again via Twitter, Trump indicated Tuesday that he believed the intelligence briefing was delayed because the experts' review of "so-called 'Russian hacking'" was still in progress. However, a U.S. official told VOA on the condition of anonymity that, given the sensitivity about the president-elect's intelligence briefings, "there was no delay" in briefing him.

Intelligence Briefings Nixon
FILE - CIA Director John Brennan speaks in Yorba Linda, California, Aug. 24, 2016.

Central Intelligence Agency chief John Brennan told the Public Broadcasting Service, "I would suggest to individuals that have not yet seen the report, who have not yet been briefed on it, that they wait and see what it is that the intelligence community is putting forward before they make those judgments.”

"He does receive routine intelligence briefings," the official added, indicating Trump was briefed Tuesday, although there might have been a "disconnect" regarding Trump's expectations for the briefing.

Last week's statement by U.S. security officials expanded on the intelligence community's public assertion in October that Russia directed the hacks of U.S. officials and political organizations and the subsequent leaks of the material to websites like and WikiLeaks.

The statement blamed the activity on Russian intelligence services and said it was "part of a decade-long campaign of cyber-enabled operations directed at the U.S. government and its citizens."

VOA's Michael Bowman contributed to this story.