“Yes, they continue to produce fissile material,” he told the committee, using the term for nuclear material that can be used in a bomb.
His testimony amounted to an elaborate cleanup effort by the United States’ top diplomat for Mr. Trump’s performance in Helsinki, during which he cast doubt on his own intelligence community’s conclusion that Russia had interfered in the 2016 presidential election. The meeting with Mr. Putin was followed by a week of halfhearted walk-backs and position shifts that have left many lawmakers questioning Mr. Trump’s ability to be tough with Russia.
Under blistering pressure for details of the talks, Mr. Pompeo shot back: “Presidents are entitled to have private meetings.”
At times, he dismissed Democratic senators’ attempts to elicit answers as politically motivated. “I understand the game that you’re playing,” he told Senator Bob Menendez, of New Jersey, the panel’s top Democrat.
“If President Obama did what President Trump did in Helsinki, I’d be peeling you off the Capitol ceiling,” Mr. Menendez said later.
The criticism came from both parties. Senator Bob Corker, Republican of Tennessee and the chairman of the committee, opened the session by saying that Mr. Trump had been “submissive and deferential” to Mr. Putin in Helsinki, and derided the administration’s foreign policy as an incoherent “ready, fire, aim” approach.
“We are antagonizing our friends and placating those who clearly wish us ill,” Mr. Corker said. “It’s the president’s actions that create tremendous distrust in our nation, among our allies — it’s palpable.”
When Mr. Corker pressed him on what motivates the president to “purposely create distrust in these institutions” by questioning his commitment to NATO or whether Russia attacked the 2016 election, Mr. Pompeo took exception.
“Some of the statements achieve important policy outcomes for the United States,” he said.
“And some,” Mr. Corker replied, “are very damaging.”
In an apparent attempt to accomplish what the president’s own statements had not, Mr. Pompeo came armed with a formal declaration refusing to recognize Russia’s seizure of Crimea in 2014. He insisted to a packed hearing room that the president was “well aware of the challenges that Russia poses” and had taken “a staggering number of actions to protect our interests,” calling them “proof” that Mr. Trump was willing to hold Moscow to account.
In one testy exchange with Senator Tom Udall, Democrat of New Mexico, who asked whether Mr. Trump’s financial ties with Russia could be driving foreign policy, Mr. Pompeo began reciting a litany of actions the administration has taken against Moscow, offering to send a full list to the committee — including imposing sanctions, expelling diplomats, closing a consulate and providing weapons to Ukraine, where the military is fighting Russia-backed separatists.
“We’ll back a truck up and get it on in here,” Mr. Pompeo said with a glare.
Just before the hearing began, the White House announced it was delaying an invitation to Mr. Putin to meet with Mr. Trump this fall in Washington. A statement by John R. Bolton, the national security adviser, said the follow-up meeting between the two presidents should take place at the conclusion of the special counsel’s investigation into Russian election interference — “after the Russia witch hunt is over, so we’ve agreed that it will be after the first of the year.”
Russian officials had not yet committed to the invitation.
In his testimony, Mr. Pompeo sought but fell short of assuring senators that the United States would never acknowledge Russia’s annexation of Crimea. He did not directly answer whether sanctions to punish Russia for seizing the Ukrainian peninsula would remain in place in perpetuity.
Instead, Mr. Pompeo repeatedly restated United States policy, saying that after the Helsinki summit meeting, 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.
Mr. Menendez told Mr. Pompeo that American citizens and their elected officials have heard more about what happened in the closed-door Helsinki meeting from Moscow than from their own president.
“We don’t know what the truth is because nobody else was in the room where 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 that 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 spent much of the hearing attempting to convince senators it that it was the Trump administration’s policies — not the president’s own words — that mattered. At times, under questioning from the lawmakers, that meant the secretary of state contradicted Mr. Trump.
That was the case when it came to Mr. Trump’s frequent complaints that NATO allies have been delinquent in paying their bills to the United States — a mischaracterization that Mr. Corker called out.
“That’s a misnomer, is it not?” Mr. Corker said. “These NATO countries are not not paying bills to the United States, as sometimes is projected.”
Mr. Pompeo agreed. “That’s correct,” he said.
At another point, Senator Jeanne Shaheen, Democrat of New Hampshire, asked whether Mr. Trump and Mr. Putin had discussed scaling back American military presence in Syria. Mr. Pompeo repeated that “there’s been no change to U.S. policy.”
“That’s not exactly the question,” Ms. Shaheen responded.
“It’s what matters,” Mr. Pompeo answered back testily. “What matters is what President Trump has directed us to do following his meeting.”
But he later conceded that Mr. Trump’s words reflect United States policy.
“It is the case that the president calls the ball,” Mr. Pompeo said. “His statements are, in fact, policy.”
Mr. Pompeo’s decision to concede that American intelligence agencies believe North Korea is still producing nuclear fuel was significant.
It runs counter to the narrative that Mr. Trump has been pressing, one in which the North is making good progress on its promises to him in the June summit meeting in Singapore. The acknowledgment of continued nuclear production suggests that even as the negotiations inch forward, the magnitude of the problem is increasing.
For Kim Jong-un, the North Korean leader, the continued production of nuclear material may be a pressure tactic. The C.I.A. — which Mr. Pompeo headed last year — believes that Mr. Kim will never give up all of his nuclear ability, but may negotiate a reduction in parts of it.