US Secretary of State Mike Pompeo has unloaded on his Obama-era predecessor John Kerry for “actively undermining” U.S. policy on Iran by meeting several times recently with the Iranian foreign minister, who was his main interlocutor in the Iran nuclear deal negotiations, AP reported.

In unusually blunt and caustic language, Pompeo said Friday that Kerry’s meetings with Mohammad Javad Zarif were “unseemly and unprecedented” and “beyond inappropriate.” President Donald Trump had late Thursday accused Kerry of holding “illegal meetings with the very hostile Iranian Regime, which can only serve to undercut our great work to the detriment of the American people.”

Pompeo said he would leave “legal determinations to others” but slammed Kerry as a former secretary of state for engaging with “the world’s largest state-sponsor of terror” and telling Iran to “wait out this administration.” He noted that just this week Iranian-backed militias had fired rockets at U.S. diplomatic compounds in Iraq.

“You can’t find precedent for this in U.S. history, and Secretary Kerry ought not to engage in that kind of behavior,” an agitated Pompeo told reporters at the State Department. “It’s inconsistent with what foreign policy of the United States is as directed by this president, and it is beyond inappropriate for him to be engaged.”