President Trump responded to the massive cyberattack on U.S. government departments and agencies and private companies on Twitter Saturday, claiming the "Fake News Media" is exaggerating the extent of the hack.

Why it matters: Trump, who had been silent on the attack until now, claimed that China may be responsible, contradicting Secretary of State Mike Pompeo and other governmental officials who have said that the breach was carried out by Russia.

Context, via Axios' Kyle Daly: Cybersecurity experts, intel officials and policymakers universally agree the hack was the work of a unit of Russian cyber operators known as Cozy Bear, believed to be backed by Vladimir Putin’s intelligence services.

• And there’s widespread concern that they’re still in U.S. government and corporate computer systems, undetected.

Our thought bubble: There’s a lot we still don’t know, but the growing list of key federal agencies struck alone is cause for serious concern. This may turn out to be the most consequential hack in U.S. history, and one that has spurred lawmakers of both parties to call for a firm response.

• Trump’s refusal to acknowledge what his own intelligence and national security experts are surely telling him will come as welcome news to the Kremlin.

What he's saying: "The Cyber Hack is far greater in the Fake News Media than in actuality. I have been fully briefed and everything is well under control," Trump said in a tweet.

• "Russia, Russia, Russia is the priority chant when anything happens because Lamestream is, for mostly financial reasons, petrified of discussing the possibility that it may be China (it may!). There could also have been a hit on our ridiculous voting machines during the election, which is now obvious that I won big, making it an even more corrupted embarrassment for the USA."

Between the lines, via Axios' Jonathan Swan: A gap is widening between the president and his secretary of State on this urgent matter of national security. Pompeo faces a choice in the coming days — continue to tell the truth about the hack and begin to admit reality about the election.

• As Trump's national security officials gather facts on the attack, he is spending ever-greater amounts of time discussing conspiracy theories with allies including lawyer Sidney Powell.

The president’s tweets are a continuation of his broad defense of Russia.

• Throughout his time in office, Trump has defended the country against multiple claims, including that it interfered in the United States' 2016 election and the nation paid the Taliban to kill U.S. troops in Afghanistan.
• The president also continued to spread false election claims by suggesting without evidence that the hack influenced the outcome of the 2020 presidential race.

The big picture: The U.S. Cybersecurity and Infrastructure Security Agency has said the hack "poses a grave risk to the Federal Government and state, local, tribal, and territorial governments as well as critical infrastructure entities and other private sector organizations."

• President-elect Biden said on Thursday that the hack "is a matter of great concern" and promised to impose "substantial costs" to those responsible for the attack.
• Microsoft President Brad Smith said on Thursday that it effectively amounted to "an attack on the United States and its government and other critical institutions, including security firms."

A Trump administration official told Axios on Friday that the government still doesn't know the extent of the breach, which may have started in March and continued all through the election.

• The hack is known to have breached the Departments of Defense, State, Homeland Security, Treasury, Commerce and Energy and its National Nuclear Security Administration — plus the National Institutes of Health.
• Multiple global corporations were also infiltrated.

Go deeper: What we know about Russia's sprawling hack into federal agencies