Sally Yates, the Obama-appointed deputy attorney general who briefly served as acting attorney general before being fired by President Trump, became something of a heroine to the president's opponents Monday with her testimony before a Senate Judiciary Subcommittee. Appearing with former Director of National Intelligence James Clapper — former Obama national security adviser Susan Rice refused to testify — Yates talked about Trump, Russia, Mike Flynn, the travel ban executive order and more.

The only problem was, Yates' testimony added little to the public's knowledge about Trump, Russia, Michael Flynn, or the travel ban executive order. On a number of occasions, Yates refused to answer questions, explaining that to do so would reveal classified information. But on other occasions, senators just didn't ask, or didn't allow Yates to fully answer questions. The bottom line was that many of the things we didn't know before the hearing, we still didn't know after. Here are five:

1) What did Flynn do? Yates told the subcommittee about her Jan. 26 visit to the White House to tell White House counsel Don McGahn of serious concerns about Flynn, the newly-installed national security adviser. Flynn's transition conversation(s) with Russian ambassador Sergey Kislyak had been wiretapped, and Yates had read the transcripts. In addition, Yates, along with a Justice Department associate who went with her to the White House, knew what Flynn had told the FBI when agents questioned him on Jan. 24.

"The first thing we did was to explain to Mr. McGahn that the underlying conduct that General Flynn had engaged in was problematic in and of itself," Yates told the subcommittee.

But what was the underlying conduct? Was it the very fact that the incoming national security adviser talked to the Russian ambassador during the transition? Was it that they had discussed U.S. sanctions on Russia? Was it Flynn not telling Vice President Mike Pence the truth about those conversations? Whatever it was, it left Flynn "compromised" and vulnerable to "blackmail" by the Russians, Yates testified.

One question went unasked for a long time, but finally Democratic Sen. Chris Coons asked it, simply: "What was that underlying conduct?"

"My knowledge of his underlying conduct is based on classified information," Yates said. "And so I can't reveal what that underlying conduct is."

The mystery went unsolved. A number of knowledgeable former government officials, like Bush national security adviser Stephen Hadley, have said that there simply wouldn't be anything wrong with Flynn talking with Kislyak, nor would there be anything wrong with the two of them discussing sanctions. It's not clear whether Yates agrees or disagrees. Nor is it clear whether Flynn was doing something else we don't know about.

"I obviously cannot go through [it] with you today because it's classified," Yates said on another occasion. "But we took [McGahn] through in a fair amount of detail of the underlying conduct, what Gen. Flynn had done, and then we walked through the various press accounts and how it had been falsely reported."

While that suggests Flynn's conduct involved things that have already been reported, it's not entirely clear one way or the other. Yates offered nothing to clarify things for the public.

2) Why did Yates deem the Trump travel ban executive order unconstitutional? As acting attorney general, Yates ordered the Justice Department not to defend the president's executive order temporarily halting admissions of some travelers from a few countries that have extensive records of terrorism. Before the Senate Monday, Yates said — with some prodding — that she believed the order was both unlawful and unconstitutional. But she left unanswered questions when she was asked why she overruled the Justice Department's Office of Legal Counsel, which had ruled the executive order lawful.

Although no senator gave her the chance to explain in depth, Yates seemed to suggest that the plain black-and-white text of the order might have been lawful and constitutional, but that it was not when viewed in the context of President Trump's campaign statements about Muslims. (That is a position taken by the various federal judges who have so far ruled against the order.)

The Office of Legal Counsel lawyers "do not look beyond the face of the executive order, for example, [to] statements that are made contemporaneously or prior to the execution of the E.O. that may bear on its intent and purpose," Yates said. "That office does not look at those factors, and in determining the constitutionality of this executive order, that was an important analysis to engage in, and one that I did."

"It was appropriate for us to look at the intent behind the president's actions, and the intent is laid in and out his statements," Yates added.

What were the Trump statements that Yates believed made the executive order unlawful and unconstitutional? Would the same order have been lawful and constitutional had Trump remained publicly quiet? Yates did not elaborate.

It's not a settled question. While it is true that some federal judges have agreed with Yates, it's also true that some have disagreed. A group of judges on the 9th Circuit dissented from the Yates position. And even as Yates spoke Monday, some judges on the 4th Circuit were expressing serious skepticism about that position. So why would Yates, as a holdover, acting attorney general, take such momentous action? The answer was not clear. As Republican Sen. John Kennedy said to Yates, "Who appointed you to the United States Supreme Court?"

3) Did Yates come up with a new, after-the-fact explanation for her action? Several times during the hearing, Yates said she opted not to defend the travel ban order because such a defense would not be "based in truth." "All arguments have to be based on truth because we're the Department of Justice," she said.

"I believed that any argument that we would have to make in its defense would not be grounded in the truth, because, to make an argument in its defense, we would have to argue that the executive order had nothing to do with religion, that it was not done with an intent to discriminate against Muslims," Yates said. "I don't believe that there are reasonable legal arguments that are grounded in truth that can be made in defense of his argument that the travel ban was not intended to have an impact, a religious impact, and to disfavor Muslims."

As Jack Goldsmith, a Harvard Law professor and former George W. Bush Justice Department official, wrote Monday night, the "truth" argument was quite different from the one Yates made in January, when she ordered the Department not to defend the Trump order. Back then, she wouldn't even say that the order was unlawful, or that it was unconstitutional. Yates "gave a series of muddled reasons for her decisions," Goldsmith noted, "some based on her uncertainty whether the EO was lawful … and some based on policy considerations."

It is not clear whether Yates tailored the rationale she presented to the subcommittee to conform to subsequent judicial rulings. But it is a fact that she told a different story, and the new story presented to the Senate happened to align with those subsequent rulings against the executive order. Meanwhile, the full story of her action on the order remains untold.

4) Remember collusion? The key question at the heart of the Russia affair has always been whether Trump or his associates colluded with Russians in an attempt to influence the 2016 election. No one, senator or witness, presented any new evidence to support the collusion theory. But one talking point favored by Trump defenders took a serious hit.

Back in March, Clapper (who left office on Jan. 20) was asked on NBC's "Meet the Press" whether he had seen any evidence of collusion. He said he had not. The statement was quickly embraced by Trump defenders; if the nation's top intelligence official saw no evidence of collusion, then it seemed reasonable to conclude there wasn't any.

At the hearing, subcommittee chairman Sen. Lindsey Graham asked Clapper if his "Meet the Press" statement was still accurate. "It is," Clapper answered. The only problem was, Clapper went on to explain that he did not even know about the FBI's counterintelligence investigation into the Russia affair — that was the investigation, begun in July 2016, whose existence was revealed publicly by FBI Director James Comey in congressional testimony in March. "Given its sensitivity, even the existence of a counterintelligence investigation is closely held, including at the highest levels," Clapper said. "I was not aware of the counterintelligence investigation."

It's safe to say that from now on, Clapper's I-have-seen-no-evidence-of-collusion statement will have far less value to Trump defenders.

5) Who leaked? Transcripts of wiretapped conversations, even the existence of wiretapped conversations, are highly, highly classified. Republicans have for months wanted to know who leaked them to the press in the case of Flynn. Both Yates and Clapper said they had never, ever leaked classified information and did not know who did in the Flynn case. They offered no insights about how such leaks might have occurred. Of all the unanswered questions in this case, that is the one most likely to remain unanswered forever.