Defense Secretary Jim Mattis at a press conference on Tuesday echoed President Trump’s warning to Iran and said it is time for Iran to “shape up” and stop its irresponsible behavior throughout the Middle East.

A reporter asked Mattis about Trump’s recent tweet about Iran, what “red line” Iran would have to cross to prompt a military reaction, and whether he was concerned about any miscalculation with Iran. Mattis responded:

On Iran, I think what we have to look at is the destabilizing influence that Iran has consistently portrayed and demonstrated throughout the region. And the only reason that the murderous Assad is still in power — the primary reason — is because Iran has stuck by him, reinforced him, funded him, we see the same kind of malfeasance down in Yemen, where they’re fomenting more violence down there.

We’ve seen their disruptive capabilities demonstrated from Bahrain to the Kingdom. And it’s time for Iran to shape up and show responsibility as a responsible nation. It cannot continue to show irresponsibility as some revolutionary organization that is intent on exporting terrorism, exporting disruption across the region. So I think the president was making very clear that they’re on the wrong track.

Trump had tweeted to Iranian President Hassan Rouhani on Sunday:

To Iranian President Rouhani: NEVER, EVER THREATEN THE UNITED STATES AGAIN OR YOU WILL SUFFER CONSEQUENCES THE LIKES OF WHICH FEW THROUGHOUT HISTORY HAVE EVER SUFFERED BEFORE. WE ARE NO LONGER A COUNTRY THAT WILL STAND FOR YOUR DEMENTED WORDS OF VIOLENCE & DEATH. BE CAUTIOUS!

Trump’s tweet came in response to remarks made by Iranian President Hassan Rouhani earlier on Sunday. According to an Iranian state news agency, Rouhani had told a gathering of Iranian diplomats, “America should know that peace with Iran is the mother of all peace, and war with Iran is the mother of all wars.” He also reportedly said, “Mr. Trump, don’t play with the lion’s tail, this would only lead to regret.”

Secretary of State Mike Pompeo on Sunday delivered an address at the Reagan Presidential Library attacking the Iranian regime, and appealing to the Iranian people. “After 40 years of tyranny, the proud Iranian people are not staying silent about their government’s abuses. We will not stay silent either,” he said.

The press conference took place at Stanford University’s Hoover Institute, after a two-day ministerial with Secretary of State Mike Pompeo and their Australian counterparts.

Mattis, an Iran hawk and retired four-star Marine general who served as the commander in charge of the Middle East, had clashed with the Obama administration over Iran.