President Trump needs to lead NATO allies in an international effort to counter Russian cyberattacks against Western powers and Russia's decadeslong attempt to thwart the U.S., a senior Senate Democrat warns.

“This threat existed long before President Trump took office, and unless he takes action now, it will continue long after his administration,” Sen. Ben Cardin, the ranking member on the Foreign Relations Committee, said in a Wednesday statement.

The Maryland Democrat issued that warning alongside a report compiled by his team that chronicled two decades of Russian “attacks on democracy,” starting with President Vladimir Putin’s consolidation of power in his home country. That history dovetails findings by Trump administration officials and congressional Republicans, who have observed that Russia’s interference in the 2016 elections was a continuation of previous tactics.

But Cardin is also using it to put pressure on the president.

“Never before in American history has so clear a threat to national security been so clearly ignored by a U.S. president,” the preface to the report reads.

The Senate Democratic report amplifies suspicions that Russian intelligence officials staged a series of terrorist attacks in Moscow in 1999. Putin’s response to the bombings, which took place shortly after his emergence as the chief political power in Russia, solidified his popularity. The report also chronicles the deaths of numerous Putin critics and notes how Kremlin-backed media outlets have expanded into the West.

“Mr. Putin sees successful democracies, especially those along Russia’s periphery, as threats to his regime because they present an attractive alternative to his corrupt and criminal rule,” the report states. “Mr. Putin has thus made it a priority of his regime to attack the democracies of Europe and the United States and undermine the transatlantic alliance upon which Europe’s peace and prosperity have depended upon for over 70 years.”

Trump has wavered in blaming Putin for the cyberattacks against the Democratic Party in the 2016 elections. While his national security team has agreed Russia was responsible for the theft of documents and their release to WikiLeaks, Trump has emphasized his innocence in any alleged collusion between his campaign and the Russian government and has called it a “hoax” designed to discredit his victory.

“Since the first day I took office, all you hear is the phony Democrat excuse for losing the election, Russia, Russia, Russia,” the president tweeted in November. Following a meeting with Putin in July, Trump suggested that “you wouldn’t have found out about it," if Russia had truly been involved in the cyberattacks.

“Look: Something happened and we have to find out what it is, because we can’t allow a thing like that to happen to our election process,” Trump told Reuters. “So something happened, and we have to find out what it is.”

CIA Director Mike Pompeo, a former Kansas Republican lawmaker who Trump appointed to lead the intelligence agency, has been more emphatic. FBI Director Christopher Wray, another Trump appointee, likewise has told lawmakers that he is establishing a team to develop a plan to prevent Russian interference in the 2018 and 2020 elections.

That’s not good enough for Cardin. “Without leadership from the president, any attempt to marshal such a response will be inherently weakened at the outset,” his report says.

Cardin proposes that Trump “declare that it is U.S. policy to counter and deter all forms of Russian hybrid threats against the United States and around the world.” That pledge would be followed by a series of offensive and defensive measures, including coordination with European allies to develop systems that mitigate the effectiveness of asymmetric Russian moves.

“The U.S. government should also call a special meeting of the NATO heads of state to review the extent of Russian government-sponsored cyberattacks among member states and develop formal guidelines on how the Alliance will consider such attacks in the context of NATO’s Article 5 collective defense provision,” the report suggests.

Cardin also calls for the United States to embarrass Putin personally by “mak[ing] public any intelligence related to Mr. Putin’s personal corruption and wealth stored abroad,” along with freezing the assets of Putin’s allies and developing a new sanctions policy for retaliating against future cyberattacks.

“President Trump must be clear-eyed about the Russian threat, take action to strengthen our government’s response and our institutions, and — as have other president’s in times of crisis — mobilize our country and work with an international coalition to counter the threat and assert our values,” Cardin said.