Russian President Vladimir Putin “ordered an influence campaign” aimed at the 2016 election with the objective of undermining confidence in the U.S. democratic process and boosting President-elect Donald Trump’s chances, according to an assessment from U.S. intelligence agencies.

This should outrage every American. And Washington should unite to punish Russia for a direct attack on our democracy.

Trump should lead that effort. It took until Wednesday’s news conference for him to declare that “I think it was Russia.” But moments later he seemed to qualify the offense. “We talk about the hacking and hacking’s bad and it shouldn’t be done,” he said. “But look at the things that were hacked, look at what was learned from that hacking.”

Trump was referring to Hillary Clinton and the 2016 campaign. But what the U.S. really learned was that Russia brazenly attacked the core of our democracy, and Trump hasn’t acknowledged the gravity of that offense. What’s more, when the report was released last week, Trump irresponsibly denigrated the intelligence agencies that as president he will rely on.

He did so again on Wednesday when he suggested intelligence agencies may have been behind the release of documents presented to Trump and President Obama that included allegations that Moscow has compromising financial and personal information on the president-elect, and that Trump campaign officials interacted with the Russian government.

Trump has denied the unsubstantiated allegations. But the broader issue of Trump’s relationship with Russia and his continued defense of Putin — despite Russian aggression in Ukraine, Georgia and Syria, military provocations in Europe, and meddling in other Western elections — is deeply problematic.

There are signs that Congress will respond appropriately. Ten senators, including five Republicans and five Democrats, have introduced legislation to impose sanctions on Russia for hacking and its actions in Ukraine and Syria. (Some of the sanctions would go beyond those imposed by Obama.) A similar measure is advancing in the House.

If the bill passes and Trump vetoes it, Congress should override him. Lawmakers should also launch an independent investigation of the Russian hack and transparently communicate its findings.

Meanwhile, the Senate needs to carefully scrutinize Trump’s national security appointments. The pointed questions aimed at former ExxonMobil CEO Rex Tillerson, the secretary of state designee with extensive ties to Russia, were a good start. Wednesday’s hearings also produced some encouraging answers. Tillerson rightly characterized Russia as a “danger” to the United States and suggested he would have called for military support for the beleaguered Ukrainian government to respond to Russia cleaving Crimea.

Russia is indeed dangerous. Fortunately, the GOP has an admirable legacy of standing up to the Kremlin, whether it governed the Soviet Union or Russia. Now more than ever, congressional leaders need to build upon that record.