WASHINGTON — Tempers flared during a Senate Foreign Relations committee hearing on Wednesday over the Trump administration’s lack of accountability to Congress following two unprecedented and secretive meetings between the president and foreign adversaries in North Korea and Russia.

“Americans and the members of this committee deserve to know what the president and foreign autocrats are agreeing to behind closed doors,” New Jersey Senator Robert Menendez, the committee’s top Democrat, argued in the hearing, which had been scheduled to discuss routine nominations but quickly ventured into more pressing terrain.

Menendez added, “If the administration is unwilling to consult with this committee in a meaningful fashion on vital national security issues, then we must consider all appropriate responses.”

In June, Trump became the first ever U.S. president to participate in a face-to-face meeting with a North Korean dictator when he met with Chairman Kim Jong Un in Singapore. The Senate Foreign Relations Committee has been seeking Secretary of State Mike Pompeo’s testimony since that meeting to learn more about any agreements Trump discussed with Kim.

Pompeo has not yet informed Congress on the Trump-Kim summit and cancelled an initial plan to brief all U.S. senators a couple weeks ago.

Then, on Monday, Trump met one-on-one with Russian president Vladimir Putin in Helsinki, Finland — a meeting that took place without any U.S. foreign policy aides and which went forward despite an escalating investigation into Russian cyberattacks on the U.S. in an attempt to help Trump’s 2016 campaign.

Days before the Trump-Putin summit, Assistant Attorney General Rod Rosenstein announced the indictments of twelve Russian military intelligence officers for hacking the computers of top Democratic officials during the 2016 presidential campaign.

In both cases, Senate aides said, Congress — which is constitutionally required to provide a check on the executive branch — has no idea what the president discussed with leaders of the world’s most dangerous regimes, both of which also possess nuclear weapons.

This time, Senate Foreign Relations Committee Chairman Bob Corker of Tennessee has secured a public hearing with Pompeo to take place next Wednesday. Committee aides are now preparing for an extended hearing, most likely at least two and a half hours, they say.

Corker responded during Wednesday’s hearing with his own frustration, as the committee has failed to secure routine hearings on Russia, and the status of the U.S. relationship with NATO.

Last week, Trump appeared to question the value of the NATO alliance and complained that NATO countries were not spending enough on defense. Lawmakers of both parties have expressed alarm given the historic nature of the alliance, which has helped maintain peace in Europe since the end of World War II.

“On challenging what happened at NATO, what happened at Helsinki, I will take a backseat to no one in this body,” Corker said in the hearing.

“The first step is getting them up here, like we both pushed for. And it is now happening,” said Corker. “And I agree, State Department has been remiss in getting us witnesses on numbers of topics,” he added.

According to aides who’ve been trying to arrange meetings with top Trump advisers and State Department experts, the frustration extends even to more routine hearings. Some of the backlog stems from an understaffed State Department, where many important diplomatic positions remain unfilled.

It’s unlikely Pompeo’s appearance will be enough to quell the uproar on Capitol Hill from Trump’s Helsinki meeting with Putin in which he criticized the nation’s intelligence agencies, said the U.S. had acted foolishly in its past behavior toward Russia and refused to condemn a 2016 Russian cyber attack.

Trump refused to allow his team of advisers to participate in the two-hour meeting with Putin, a former KGB agent, opting to speak with him alone instead. The only American witness was the president’s translator.

Speaking to reporters on Capitol Hill, Connecticut Sen. Richard Blumenthal of Connecticut compared the seriousness of the situation to the September 11, 2001 terror attacks on the United States.

“This 9/11 moment demands that we do come together, issue a subpoena, not only for the translator and the notes, but also for the national security team that debriefed the president,” Blumenthal said.

Later Corker told reporters that there’s reason for concern about Trump’s meeting with Putin, especially considering Trump’s conduct at the news conference.

“We’re looking at the precedent” in regards to calls for the notes the translator took during President Trump’s meeting with Putin, said Corker. Later, he said Trump’s conflicting statements about whether Russia is seeking to meddle in U.S. elections are “baffling.”

“I don’t know what drives this,” he said. “I don’t know what it is about the president’s relationship with Putin that causes him to doubt, to trust him over our intelligence community, but it’s really damaging morale.”

A number of senators also continue to be agitated over North Korea.

Aides say it remains unclear what kind of a potential deal Trump discussed with Kim Jong-un, including whether it would take the shape of a treaty. In fact, it’s unclear that any kind of framework at all was agreed to by the two leaders.

After jetting home from Singapore, Trump declared North Korea was no longer a national security threat to the U.S. and told Americans to “sleep well.” The statement contradicted subsequent U.S. intelligence reports that the hermit country had done nothing to slow down or destroy nuclear weapons facilities.

“Is America any safer from the threat of North Korea? We have no idea. And now, we have what may seem as unlimited questions about the summit in Helsinki,” said Menendez.

“Pro-Kremlin media at this moment are putting out more information supposedly about agreements that were arrived by President Trump with President Putin, that anything that I know as the senior most Democrat on this committee,” he added.

In the House, Democrats are also readying responses, though the focus there is on stopping an amendment to a Defense spending bill that would water down sanctions on Russia. It would allow the Trump administration to make exceptions for countries seeking to purchase military weapons from Russia, a loophole of significant consequence given Russia’s volume of sales to nations other than the U.S.

The Senate did not include such a resolution in its defense spending authorization bill and representatives from both chambers will meet in a conference this week to hash out differences.