The Department of Justice will investigate the mysteriously missing text messages sent by two FBI agents, Attorney General Jeff Sessions announced late Monday.

"We will leave no stone unturned to confirm with certainty why these text messages are not now available to be produced and will use every technology available to determine whether the missing messages are recoverable from another source," Sessions said in a statement.

"I have spoken to the Inspector General and a review is already underway to ascertain what occurred and to determine if these records can be recovered in any other way. If any wrongdoing were to be found to have caused this gap, appropriate legal disciplinary action measures will be taken," he continued.

FBI agent Peter Strzok and FBI lawyer Lisa Page -- who were having an extramarital affair -- sent thousands of texts back and forth about President Trump during the presidential campaign. Special counsel Robert Mueller quietly reassigned Strzok after House investigators uncovered the text messages.

But in a bizarre twist, the FBI told lawmakers in a letter on Sunday that the bureau had somehow lost text messages between Strzok and Page over a five-month period, claiming problems with mobile phones, including "rollouts, provisioning, and software upgrades."

In an even more bizarre coincidence, the missing text messages occurred between December 14, 2016 to May 17, 2017. May 17 was the day Robert Mueller was appointed special prosecutor, and he ordered all data preserved for the probe.

Still more bizarre: The time period was also the height of the FBI’s investigation into allegations of collusion between Trump and Russia -- on which Mr. Strzok was a lead investigator. Strzok also was instrumental in clearing Hillary Clinton over her email scandal -- when more than 30,000 emails also went missing.

Trump is following the story closely, and posted a tweet early Tuesday.

Sessions said his DOJ will get to the bottom of it all. "The Inspector General has been reviewing these texts based on 'allegations that Department or FBI policies or procedures were not followed... and that certain underlying investigative decisions were based on improper considerations,'" Sessions said.

"Six congressional committees made a request to the Department of Justice for FBI text messages between two FBI employees from July 1, 2015 to July 28, 2017, which the Department agreed to produce as quickly as possible," the attorney general noted in his statement.

"If we are successful, we will update the congressional committees immediately."

Three Republican House committee chairmen put out a joint statement on Monday voicing concern about the missing text messages. GOP Rep. Lee Zeldin of New York also urged Congress to subpoena the cellphone providers in order to recover the messages.

"Congress must do everything it can to recover these critical text messages, including subpoenaing Strzok and Page's cell carriers and requesting the FBI perform a full forensic exam of their employees' phones in an attempt to recover the messages," Zeldin said in a statement