The FBI wiretapped former Trump campaign chairman Paul Manafort before and after the election because of suspicious ties to the Ukrainian government, according to recent reporting by CNN.

“It’s a big deal,” said national security expert Juliette Kayyem on Boston Public Radio today. “[It picked up] dealings that he may have had with foreign countries related to what he could do for them throughout the campaign, and the White House, so it’s significant.”

Kayyem explained that the warrant that allowed for the wiretap had to be authorized by a special court to make sure it complied with the Foreign Intelligence Surveillance Act, or FISA.

This process of justification, explained Kayyem, would require more than tax evasion or a vendetta against Manafort by the FBI. She said they would have to have a “foreign intelligence nexxus.”

“The wiretaps are not for law enforcement purposes,” she said. “They are for intelligence gathering purposes: what did he know and what was he promising?”

Kayyem fought back against rumors that the FISA court acceptance is just a “rubber stamp” without a critical examination.

She said that high acceptance percentages are explained by how few people actually come before the FISA court.

“There’s a court that’s looking at this, their standards very high, there’s not FISA wiretaps all over, not everyone has it and the fact that they sought the application, kept the application when they knew that this man was the campaign manager for the person who had the nomination, by this stage means ... they did such an unbelievable rigorous review,” said Kayyem.

To what extent did the Russians or any other country know that this was part of Manafort's plan? That is a totally legitimate question to ask right now, because I don't understand how Manafort became campaign manager.

She raised concerns about Manafort’s conversations with foreign governments before his official involvement with the Trump campaign, speculating that perhaps Russian officials knew he was on his way to the White House.

“How did Manafort end up as campaign manager for a man he did not know very well, who didn’t have strong ties through the family? Kayyem asked. “To what extent did the Russians or any other country know that this was part of Manafort’s plan? That is a totally legitimate question to ask right now, because I don’t understand how Manafort became campaign manager.”

National security expert Juliette Kayyem is the founder of Kayyem Solutions, host of the SCIF podcast and a CNN and WGBH contributor. To hear her interview in its entirety, click on the audio player above.