Former Bush administration Attorney General Michael Mukasey joins ABC's Martha Raddatz on 'This Week' to discuss the wiretapping accusations made by President Trump on Twitter on Saturday morning:



I'd bet a good lawyer could make a great case out of the fact that President Obama was tapping my phones in October, just prior to Election! — Donald J. Trump (@realDonaldTrump) March 4, 2017

Is it legal for a sitting President to be "wire tapping" a race for president prior to an election? Turned down by court earlier. A NEW LOW! — Donald J. Trump (@realDonaldTrump) March 4, 2017

MICHAEL MUKASEY, FORMER U.S. ATTORNEY GENERAL: Well, I don't do tweets.



RADDATZ: You heard about them.



MUKASEY: Yeah, I hear about them, but I don't do tweets and for good reason. It's not the' ideal medium in which to get an idea across.



This is the difference between being correct and being right. I think the president was not correct certainly in saying that President Obama ordered a tap on a server in Trump Tower. However, I think he's right in that there was surveillance and that it was conducted at the behest of the attorney -- of the Justice Department through the FISA court.



RADDATZ: And what do you base that on?



MUKASEY: I base that on news reports that you mentioned in the last spot. I also base it on kind of inadvertent blurting out by Adam Schiff that his committee wants to talk to the counterintelligence agents at the FBI who were involved in this. Now, what that means is this is part not of a criminal investigation, but of an intelligence gathering investigation.



The FBI has got two functions. They investigate crimes and they gather intelligence. They started gathering intelligence in '08 based on guidelines that we put in place.



They tried to get – apparently tried to get a wiretap based on their criminal investigation function in June. That was turned down. They then tried to get, and got, an order permitting them to conduct electronic surveillance in October. This is October of 2016.



So that's when, apparently, that's when...



RADDATZ: And again you're basing this on news reports as well.



MUKASEY: And on, and on, Adam Schiff.



RADDATZ: And on Adam Schiff. If a wiretap did exist, it would have to have been approved by a FISA court based on real evidence. So, if there was a wiretap, does that mean there were suspicious things going on between the Trump administration and the Russians?



MUKASEY: It means there were some basis to believe that somebody in Trump Tower may have been acting as an agent of the Russians, for whatever purpose, not necessarily the election, but for some purpose.



And the FBI keeps track of people who act as agents of foreign governments. They keep track of people who act as agents of the Chinese, the Russians, the Israelis, everybody.



RADDATZ: Some of the evidence may have been gleaned from classified means. Is there any way to verify these claims in the press or Trump's claims so the American people can really understand what's going on here?



MUKASEY: The only way to verify, whether there was a -- whether there was electronic surveillance is to disclose the warrant and to disclose the fruits of it. And that should not be done even in a political storm as hot as this one.



"This is the difference between being correct and being right," Mukasey said about Trump's accusation of Obama. "I think the president was not correct certainly in saying that President Obama ordered a tap on a server in Trump Tower. However, I think he is right in that there was surveillance, and that it was conducted at the behest of the... Justice Department through the FISA court."President Obama's Justice Department made two requests in June and October of 2016 to the Foreign Intelligence Surveillance Court (FISA) to monitor communications involving Donald Trump and several advisers. Because the first was denied, the second was narrower and focused on a computer server in Trump Tower suspected of transmitting links to Russian banks."It means there were some basis to believe that somebody in Trump Tower may have been acting as an agent of the Russians, for whatever purpose, not necessarily the election, but for some purpose. And the FBI keeps track of people who act as agents of foreign governments," he said. "They keep track of people who act as agents of the Chinese, the Russians, the Israelis, everybody."Transcript courtesy of ABC: