WASHINGTON (Reuters) – A former U.S. diplomat who served under Republican President George W. Bush criticized the Trump administration on Wednesday for failing to do more to investigate allegations that Russia sought to meddle in the 2016 U.S. election.

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“Russia’s going to do this again,” Nicholas Burns, who was undersecretary of state from 2005 to 2008, testified to the Senate Intelligence Committee.

“Russia’s our most dangerous adversary in the world today, and if he continues to refuse to act, it’s a dereliction of the basic duty to defend the country,” Burns said.

Burns, now a professor at Harvard University’s Kennedy School of Government, was one of four witnesses at an intelligence committee hearing about Russian efforts to influence elections in Europe.

The Senate panel and other congressional committees, as well as Department of Justice Special Counsel Robert Mueller, are investigating Russia and the 2016 presidential election and potential collusion between Moscow and President Donald Trump’s campaign.

Russia has denied such assertions. Trump, a Republican, has dismissed them as sour grapes voiced by Democrats disappointed by his victory and called them a “witch hunt.”

At a hearing last week that focused on the U.S. election, a Homeland Security official testified that Russian hackers targeted 21 state election systems in the 2016 presidential race and that a small number were breached.

On Wednesday, the intelligence committee’s ranking Democrat, Senator Mark Warner, said the panel had asked officials in 21 states to release information about the hacking.

“This week the Chairman (Republican Senator Richard Burr) and I sent a letter to all relevant state election officials asking that this information be made public,” Warner said.

“I do not see how Americans are made safer when they do not know which state elections systems Russia tried to hack,” he added.

Warner has asked the Department of Homeland Security to share the names of the 21 states, which have not been publicly identified.

The congressional probes have at times come up against concerns among Republicans about leaks of classified information and unproven assertions by Trump and others that the Obama administration improperly spied on members of Trump’s presidential campaign.

On Wednesday, Republican Senators Chuck Grassley and Lindsey Graham sent a letter to the FBI and Justice Department requesting copies of any proposed and final applications to the secretive Foreign Intelligence Surveillance Court for permission to conduct surveillance related to the 2016 election, including any related to the FBI’s ongoing Russia investigation. [/restrict]