“We are antagonizing our friends and placating those who clearly wish us ill,” Mr. Corker added, calling the Helsinki talks “perhaps the most troubling example of this troubling reality.”
The top Democrat on the committee, Senator Robert Menendez of New Jersey, told Mr. Pompeo that American citizens and their elected officials have heard more about what happened in Mr. Trump’s closed-door Helsinki meeting with Mr. Putin from Moscow than from their own president.
“We don’t know what the truth is, because nobody else was in the room when it happened,” Mr. Menendez said.
On the election interference in particular, Mr. Pompeo told the committee that the president accepts the findings that the Russian cyberattacks took place, and that he “has a complete and proper understanding of what happened.”
“I know — I briefed him on it for over a year,” Mr. Pompeo said, referring to his time as C.I.A. director.
He insisted Mr. Trump deeply respects the work of the intelligence community — a notion the president left in doubt in Helsinki when he said he had to weigh its assertions about election interference against Mr. Putin’s strong denials that it took place.
Mr. Pompeo offered what he described as “proof” that Mr. Trump holds Russia accountable when warranted, including the imposition of sanctions, the expulsion of diplomats and closing of a consulate, and the provision of arms to Ukraine, where the military is fighting Russian-backed separatists, among other steps.
And Mr. Pompeo pointed to a formal declaration, issued by the State Department just before he was scheduled to speak, that refused to recognize Russia’s annexation of Crimea and said it was “in contravention of international law.”
The statement confirmed what had already been the policy of the Trump administration, after Mr. Trump has seemed to equivocate about his position and amid assertions by Russian officials that he and Mr. Putin discussed determining the fate of the region through a referendum.
The big question from lawmakers: What happened in Helsinki?
The hearing got off to a contentious start as Mr. Pompeo pushed back strongly against attempts by Mr. Menendez to question him about what had transpired in the more than two hours of one-on-one talks between Mr. Trump and Mr. Putin.
Mr. Pompeo did not attend that meeting, and on Wednesday sidestepped specific queries about whether they discussed the possibility of relaxing sanctions on Moscow, what Mr. Trump said about Crimea, and details of their conversations about Syria.
“Presidents are entitled to have private meetings,” Mr. Pompeo said, at one point interjecting, “I understand the game that you’re playing.”
Mr. Trump was accompanied in the meeting only by an interpreter. Exactly what was said on topics such as Ukraine and Syria, as well as Russian interference in the 2016 election in the United States, remains a mystery. Mr. Trump’s conflicting statements since then have not helped matters.
Mr. Pompeo repeatedly sought refuge in restating United States policy, saying that the stance on sanctions “remains completely unchanged,” and that “no commitment has been made to change those policies.” But he did not speak to whether Mr. Trump had signaled any willingness to reconsider or modify them.
“You’re not going to answer any of the questions that would get us to the truth,” Mr. Menendez eventually shot back.
Trump and Putin ‘agree to disagree’ on Ukraine, Pompeo says.
Mr. Pompeo said on Tuesday that he had spoken to Mr. Trump about the Helsinki meeting, and that he had also spoken to Russia’s foreign minister, Sergey V. Lavrov. On Wednesday, the secretary of state said Mr. Trump and Mr. Putin “agree to disagree” on Ukraine.
Most of the world and international bodies — including the United States, Europe, the United Nation and NATO — do not recognize Russia’s seizing of the Ukrainian peninsula.
The Trump administration has repeatedly said in the past that it does not recognize Crimea as part of Russia. But Mr. Trump said during the 2016 presidential campaign that he would consider recognizing the annexation.
After the meeting in Helsinki, the Russian ambassador to the United States said that the presidents had privately discussed the possibility of a referendum to determine the future of Ukraine. But a White House spokesman for the National Security Council rejected any such referendum, saying it would have “no legitimacy.”
A Trump critic is back in the spotlight.
Among Republican lawmakers, Mr. Corker has been one of the most candid in talking critically about Mr. Trump. Wednesday’s hearing gives Mr. Corker a platform to offer an appraisal of some of the president’s recent actions on the world stage.
There is reason to expect he will unburden himself of some disapproving thoughts.
Mr. Corker was clearly distressed after Mr. Trump offered harsh words for NATO allies this month. And after Mr. Trump’s performance in Helsinki, Mr. Corker openly guessed that Mr. Putin was celebrating by having caviar.
Mr. Corker, who is not seeking re-election and therefore is less encumbered when it comes to criticizing the president, signaled that he would not hold back.
“On challenging what happened at NATO, what happened in Helsinki, I will take a back seat to no one in this body,” Mr. Corker said before the hearing.
Senators are pushing for new sanctions.
Beyond demanding answers about what happened during the Trump-Putin meeting, lawmakers also have been talking about taking additional actions to counter Russian aggression.
On Tuesday, Mr. Menendez and Senator Lindsey Graham, Republican of South Carolina, outlined legislation they are preparing to put new sanctions on Russia.
The additional sanctions, the senators said in a joint statement, are intended to “ensure the maximum impact on the Kremlin’s campaign against our democracy and the rules-based international order.”
There’s also the matter of North Korea.
It was only six weeks ago that Mr. Trump met with the North Korean leader, Kim Jong-un. Mr. Menendez noted last week that the panel had originally sought for Mr. Pompeo to appear to discuss the North Korea summit, which was held in Singapore in June.
That subject came up as well.
“Is America any safer from the threat of North Korea?” Mr. Menendez asked before the hearing began. “We have no idea.”