By Zachary Cohen, CNN

(CNN) -- Bipartisan frustration was on display Wednesday as lawmakers from both sides of the aisle grilled a defiant Secretary of State Mike Pompeo on President Donald Trump's summits with Russian leader Vladimir Putin and North Korean dictator Kim Jong Un during a Senate Foreign Relations Committee hearing.

The top US diplomat clashed with both Republicans and Democrats on several occasions -- refusing to provide substantive details about Trump's one-on-one meeting with Putin in Helsinki and the state of talks with North Korea following the President's sitdown with Kim in Singapore last month.

In what was a contentious hearing out of the gate, committee chairman Republican Sen. Bob Corker set the tone by stating many lawmakers are "filled with doubt" about the White House's foreign policy.

"I can't say it more forcefully. We really need a clear understanding as to what is going on, what our President is agreeing to, and what our strategy is on a number of issues," Corker said.

"The administration tells us, 'Don't worry, be patient, there's a strategy here.' But from where we sit, it appears that in a ready, fire, aim fashion, the White House is waking up every morning and making it up as they go," he said.

Russia at the forefront

One of the primary concerns raised by Corker and several of his Senate colleagues was the lack of clarity surrounding Trump's summit with Putin in Helsinki.

"Last week, President Trump held a summit with Vladimir Putin, someone who has violated the most fundamental international norms ... in the summit's aftermath, we saw an American President who appeared submissive and deferential," Corker said.

"We've heard that some agreements were reached, but as of yet have little idea what those might be, even though the President has already extended an invitation to Putin to come to Washington to discuss the 'implementation' of these undefined agreements," he added.

Pompeo ardently defended the administration's policies throughout three-hour long hearing but would not provide a clear answer to questions about the President's conversation with Putin.

"Presidents are permitted to have conversations with their Cabinet members that aren't repeated in public," Pompeo asserted.

Responding to questions from ranking Democrat Bob Menendez, Pompeo reiterated that "Presidents have a prerogative to choose who's in meetings."

Rather than divulge specifics of that conversation, Pompeo highlighted several policy measures he said indicated the Trump administration is committed to being tough on Russia but also open to dialogue.

He said the two leaders agreed to establish a business-to-business leadership exchange and talked about re-establishing a counterterrorism council, but did not discuss sanctions on Russia.

"Our approach has been the same: to steadily raise the costs of aggression until Vladimir Putin chooses a less confrontational foreign policy, while keeping the door open for dialogue in our national interest," he said.

"President Trump believes that two great nuclear powers should not have such a contentious relationship," Pompeo noted, adding, "he strongly believes that now is the time for direct communication in our relationship in order to make clear to President Putin that there is the possibility, however remote it might be, to reverse the negative course of our relationship."

Pompeo also said that he "personally made clear to the Russians that there will be severe consequences for interference in our democratic processes" and that Trump "accepts our intelligence community's conclusion that Russia meddled in the 2016 election."

"He has a complete and proper understanding of what happened. I know, I briefed him on it for over a year. This is perfectly clear to me personally," he added.

'It's the President that causes people to have concerns'

Prior to the hearing, Pompeo issued a statement saying the US "rejects Russia's attempted annexation of Crimea and pledges to maintain this policy until Ukraine's territorial integrity is restored."

But despite his reassurances that US policy on Russian sanctions, Crimea and election interference remains unchanged following the summit in Helsinki, lawmakers made it very clear that they remain concerned by the President's actions despite the work of top administration officials.

"Much of what you are hearing today has nothing whatsoever to do with you and I would agree with you that the policies that we are putting in place in many case are stronger than have ever been put in place. It's the President that causes people to have concerns," Corker told Pompeo.

"I think you are a patriot. Tremendous faith in (Defense Secretary James) Mattis. But it's the President's actions that create tremendous distrust in our nation, among our allies. It's palpable," he added.

But Pompeo strongly pushed back on Corker's assertion that there is a disconnect between the Trump's actions and those of the administration.

"Senator, I just disagree mostly with just about everything you just said there. You somehow disconnect the administration's activities from the President's actions. They are one in the same. Every sanction that was put in place was signed off by the President of the United States, every spy that was removed was directed by the President," he said.

"The idea that this administration is free floating, this is President Trump's administration. Make no mistake who is fully in charge of this and was directing each these activities that has caused Vladimir Putin to be in a very difficult place today," Pompeo added.

But Menendez took issue with Pompeo's suggestion that the President's public comments align with US policy.

"When the President speaks it is the policy of the United States," he said. "In one respect, I applaud this declaration about Crimea. But then he goes and says that Russia should join the G-7. Well, the reason Russia is not in the G-7 is because the invaded Ukraine. So which is the policy?"

'Fear not'

Pompeo was also repeatedly pressed for clarity on the issue of North Korea as lawmakers asked for evidence to back up the administration's claims that talks are headed in the right direction when there is little indication that Pyongyang is taking steps toward denuclearization.

"I am afraid that at this point the United States, the Trump administration is being taken for a ride," Massachusetts Democratic Sen. Ed Markey said, adding "there is no evidence."

"Fear not senator, fear not," Pompeo responded before claiming the Trump administration has made progress that has put the US in "a far better position than either of the two administrations."

"We have made incredibly clear that we will continue to enforce that sanctions regime until such time as denuclearization as we have defined it is complete," he said, repeatedly claiming that the North Koreans understand the US definition of denuclearization.

But Pompeo would not disclose what commitments on denuclearization Kim made to Trump during their summit in Singapore.

"I'm not going to get into the private commitments that have been shared," he said. "Remember where we were, right, so it all depends on what you draw as the projected line to say are we in a better place or a worse place than we would have been absent the Singapore."

"I will concede that there is an awful long way to go," Pompeo added. "I am not trying to oversell the accomplishments that we have had toward the path of denuclearization to date, there is a great deal of work to do."

When pressed further on the issue of denuclearization, Pompeo also admitted that North Korea continues to produce weapons-grade fissile material.