WASHINGTON—President Donald Trump said Thursday that an FBI agent once involved in the special counsel’s Russia probe committed “treason,” and he called for Republican investigators in Congress to conclude their probes swiftly.

In an interview with The Wall Street Journal, Mr. Trump, unprompted, labeled as “treason” a text message written by Peter Strzok, an agent at the Federal Bureau of Investigation who was removed in July as a top investigator on the special counsel’s team investigating whether Russia colluded with associates of Mr. Trump to influence the 2016 presidential election.

“A man is tweeting to his lover that if [Democrat Hillary Clinton] loses, we’ll essentially do the insurance policy. We’ll go to phase two and we’ll get this guy out of office,” said Mr. Trump, giving his interpretation of Mr. Strzok’s text message.

The Wall Street Journal interviewed President Trump in the Oval Office on Thursday. Mr. Trump spoke about his relationship with North Korean leader Kim Jong Un and signaled openness to diplomacy with North Korea. WSJ's Gerald F. Seib gives us more insight from the interview. Photo: Getty

“This is the FBI we’re talking about—that is treason,” the president said. “That is a treasonous act. What he tweeted to his lover is a treasonous act.”

Aitan Goelman, an attorney for Mr. Strzok, said: “It is beyond reckless for the president of the United States to accuse Pete Strzok, a man who has devoted his entire adult life to defending this country, of treason. It should surprise no one that the president has both the facts and the law wrong.”

The crime of treason is defined in the Constitution as aiding enemies of the U.S. or “levying war” against the nation. A spokesman for the FBI declined to comment.


In an August 2016 text, Mr. Strzok wrote: “I want to believe the path you threw out for consideration...that there’s no way he gets elected—but I’m afraid we can’t take that risk. It’s like an insurance policy in the unlikely event you die before you’re 40.”

The Journal reported last month that, according to people familiar with Mr. Strzok’s account, the “insurance policy” reference was meant to convey that the bureau needed to investigate aggressively allegations of collusion between the Trump campaign and Russia. It wasn’t intended to suggest a secret plan to harm his candidacy, they said.

Mr. Strzok was the lead agent on the FBI investigation into Mrs. Clinton’s use of a private email server when she served as secretary of state. Special counsel Robert Mueller removed Mr. Strzok from his team in July after learning that he sent texts critical of Mr. Trump.

In Thursday’s interview, Mr. Trump also said the U.S. is taking steps to ensure that Russia and any other countries don’t try to influence future elections.


“We’re going to be very, very careful about Russia and about anybody else, by the way,” Mr. Trump said.

The president declined to detail specific actions under way to protect the electoral system, beyond saying that his administration is “working on different solutions” and “all sorts of fail-safes.”

Mr. Trump, a Republican, has previously expressed skepticism about a 2017 U.S. intelligence report that said Russia sought to interfere in the 2016 election, an allegation Moscow has denied.

The president, in the interview, also forcefully defended himself against allegations of collusion between his 2016 campaign and Russia and whether he obstructed justice by firing former FBI Director James Comey last spring as the agency investigated Moscow’s alleged interference. Mr. Mueller is investigating those matters.


“Of course there was no obstruction—there was no crime,” Mr. Trump said. “They make up a crime, and the crime doesn’t exist, and then they say obstruction.”

Mr. Trump said he should get credit for firing Mr. Comey, saying “everybody wanted Comey fired.

“I should be given credit for having great insight,” he said.

Last year, lawmakers in both parties criticized Mr. Trump’s decision to fire Mr. Comey, with some Republicans calling it troubling. Lawmakers swiftly called for the appointment of an independent counsel to take over the FBI’s Russia probe.


The president said he based the decision to fire Mr. Comey on Deputy Attorney General Rod Rosenstein’s memo criticizing the then-FBI director. “He was in charge,” Mr. Trump said of Mr. Rosenstein.

Mr. Rosenstein wrote the memo about Mr. Comey at the White House’s prompting, a day after meeting with the president to discuss Mr. Comey’s job performance, the Journal previously reported. The memo didn’t expressly recommend Mr. Comey be fired.

In an NBC interview days after Mr. Comey’s termination, Mr. Trump said “this Russia thing” was on his mind when he decided to fire him. A spokesman for the FBI didn’t immediately return a request for comment.

Mr. Mueller told Mr. Trump’s lawyers last month he may want to speak with the president in the near future. The president, in Thursday’s interview, wouldn’t commit to speaking with or answering questions on obstruction of justice from Mr. Mueller.

Mr. Trump said his lawyers’ initial instinct with regard to the special counsel investigation was: “We’ll fight this.”

But after they reviewed the documents requested by the special counsel, Mr. Trump said, “They said, ‘We should be open.’ They said, ‘You never did anything wrong.’”

“To be honest, they probably were surprised, as most lawyers would be,” he said, referring to what he said was his lawyers’ conclusion that he didn’t do anything wrong.

Mr. Trump offered praise for Republican congressional investigators. Asked whether he believed the congressional investigations were nearing an end, Mr. Trump said: “I hope so.”

Mr. Trump said his call in a tweet earlier this week for Republicans to “take control” of the investigations shouldn’t be interpreted as an order to shut them down. “No, I just want them to be tough—be strong,” he said.

He also defended his eldest son’s decision to take a meeting in June 2016 at Trump Tower with a Russian lawyer tied to the Kremlin. His son, Donald Trump Jr., was promised damaging information about Mrs. Clinton.

Former White House chief strategist Steve Bannon was quoted in a new book about the administration as calling the meeting “treasonous,” though he has since said his comment was aimed at former campaign chairman Paul Manafort, who also attended the 2016 meeting at Trump Tower in Manhattan.

“What he said about my son is horrible,” Mr. Trump said.

—Del Quentin Wilber contributed to this article.

Write to Rebecca Ballhaus at Rebecca.Ballhaus@wsj.com