In his testimony before the Senate Intelligence Committee hearing on Thursday morning, former FBI director James Comey declined to answer many of the hot-button questions senators tossed at him—at least, in an “open setting.”

These moments are notable, since Comey’s refusal to answer in public indicates that the topic touches on classified information or, potentially, to what he believes to be a continuing FBI investigation.

Several senators announced their intentions to bring some of these questions up in the closed meeting they conducted with Comey following the public hearing.

Here’s a roundup:

1. The “Steele dossier”

Sen. Richard Burr, a Republican from North Carolina and the chair of the committee, asked Comey about the “Steele dossier”--a document produced by a former British intelligence officer that listed unverified allegations about Trump’s activities and connections in Russia.

The document alleges that the Kremlin colluded with Trump’s presidential campaign and claims that Russian officials have compromising evidence of Trump’s behavior that could be used to blackmail him. Trump has dismissed the contents of the dossier as false, and Russia has denied the claims.

Burr asked: “At the time of your departure from the FBI, was the FBI able to confirm any criminal allegations contained in the Steele document?”

Comey’s response: “Mr. Chairman, I don’t think that’s a question I can answer in an open setting because it goes into the details of the investigation.”

Burr followed up: “And when you read the dossier, what was your reaction, given that it was 100% directed at the president-elect?”

Comey: “Not a question I can answer in open setting, Mr. Chairman.”

Later, Sen. Angus King, the committee’s only independent senator, again brought up the Steele dossier, asking if it was being reviewed or followed up on in any way. And, again, Comey demurred, saying he couldn’t comment and that it was now the responsibility of special counsel Bob Mueller.

2. The secret channel with Russia

Sen. Martin Heinrich, a Democrat from New Mexico, asked Comey about the reports that the Trump transition team considered setting up a secret communications line with Russia. (Heinrich didn’t name him, but media reports have specified that Jared Kushner, Trump’s son-in-law and senior adviser, was behind the idea.)

Heinrich’s question was generally on the risks posed by such a move, and didn’t ask Comey to verify those reports.

But Comey began by stating for the record he couldn’t comment on “whether that happened” in the open setting of the hearing, before continuing on to describe what the risk of such a setup might be. “You spare the Russians the cost and effort to break into our communications channels by using theirs. You make it a whole lot easier for them to capture all of your conversations. Then to use those to the benefit of Russia against the United States.”

3. The investigation into Michael Flynn

Sen. King asked Comey if Michael Flynn was a “central figure” in the FBI’s Russia investigation, and Comey said he couldn’t answer in an open setting. King pressed further asking if Flynn were “part of” the investigation, and Comey again declined. King announced his intention to follow up on that in the closed session.

4. What do you know about VEB?

Shortly thereafter, King asked Comey what he knows about the Russian bank VEB. Comey responded, “Nothing that I can talk about in an open setting. I know it exists.”

VEB is a Russian state-run bank, whose full name is Vnesheconombank, under scrutiny by U.S. investigators and which is currently subject to U.S. sanctions.

The bank financed a deal involving Donald Trump’s onetime partner in a Toronto hotel tower at a key moment for the project, according to The Wall Street Journal. U.S. investigators are looking into any ties between Russian financial institutions, Trump and anyone in his orbit, according to the Journal’s reporting.

5. Did Trump collude with Russia?

Sen. Tom Cotton, a Republican from Arkansas who along with Marco Rubio was one of the members of the committee to dine with Trump two days prior, asked Comey: “Do you think Donald Trump colluded with Russia?”

Here’s Comey’s full response:

“That’s a question I don’t think I should answer in an opening setting. As I said, when I left, we did not have an investigation focused on President Trump. But that’s a question that will be answered by the investigation.”

6. The media report of Trump campaign contact with Russian intelligence

Cotton brought up a February New York Times story that claimed that Trump’s campaign and associates had repeated contacts with senior Russian intelligence officers and asked if Comey had any indication of contact between “Trump people and Russians, intelligence officers, other government officials or close associates of the Russian government.”

Comey, who said in his testimony that the New York Times story was inaccurate, wouldn’t go that step further with Cotton, saying, “That’s one I can’t answer sitting here.”

7. Flynn, again

Cotton then moved on to Flynn and a Washington Post article in January charging that the FBI had reviewed Flynn’s calls with the Russian ambassador but found nothing “illicit.” “Is this story accurate?” asked Cotton.

Comey’s response: “I don’t want to comment on that, Senator. I’m pretty sure the bureau has not confirmed any interception of communications. So, I don’t want to talk about that in an opening setting.”

Cotton then went on to press Comey in a few different ways on Flynn, all of which were deflected by Comey, so we’ll just post the rest of that exchange here, as it was transcribed by Politico:

COTTON: Would it be improper for an incoming national security adviser to have a conversation with a foreign ambassador?

COMEY: In my experience, no.

COTTON: But you can’t confirm or deny that the conversation happened and we would need to know the contents of that conversation to know if it, in fact, was proper.

COMEY: I don’t think I can talk about that in an opening setting. Again, I’ve been out of government a month. So, I also don’t want to talk about things when it’s now somebody else’s responsibility. But maybe in the classified setting, we can talk more about that.

COTTON: You stated earlier that there was an open investigation of Mr. Flynn and the FBI. Did you or any FBI agent ever sense that Mr. Flynn attempted to deceive you or make false states to an FBI agent?

COMEY: I don’t want to go too far. That was the subject of the criminal inquiry.

COTTON: Did you ever come close to closing the investigation on Mr. Flynn?

COMEY: I don’t think I can talk about that in open setting either.

COTTON: We can discuss these more in the closed setting then.

8. More on meetings with the Russians…

Sen. Kamala Harris, a former California Attorney General, who has been (like many Democrats) a vocal critic of Trump, started off her questioning by reminding Comey that they were both former prosecutors. She then jumped into it, barreling through a string questions that Comey wouldn’t answer.

HARRIS: “Are you aware of any meetings between the Trump administration officials and Russia officials during the campaign that have not been acknowledged by those officials in the White House?”

COMEY: No comment, in open setting.

HARRIS: “Are you aware of any questions by Trump campaign officials or associates of the campaign to hide their communications with Russian officials through encrypted means?”

COMEY:Same answer.

HARRIS: “In the course of the FBI’s investigation, did you ever come across anything that suggested that communication, records, documents or other evidence had been destroyed?”

COMEY: Same, same.

9. Is there anything out there that could be used to blackmail Trump?

Sen. John McCain confused a lot of people with his opening line of questioning, in which he appeared to conflate the ongoing investigation into Russian meddling in the campaign with the closed probe into Hillary Clinton’s private email server.

Later on, McCain asked Comey if he was aware of anything that would “lead you to believe that the president or members of the administration or members of the campaign could potentially be used to coerce or blackmail the administration?”

Comey responded: “That’s a subject for investigation. Not something I can comment on sitting here.”