Fox News contributor and former George W. Bush speechwriter Marc Thiessen defended President Trump's decision to order the airstrike that killed Iranian general Qassem Soleimani last week, saying that it "restored deterrence."

"[The order to take out Soleimani is] not impulsive. That was very carefully thought out strategy. And now he's restored deterrence with the Iranian regime," Thiessen said on "The Story with Martha MacCallum" Wednesday. "He's sending him [Ayatollah Ali Khamenei] a message that America will not be pushed around. You will not cross our red lines."

IRAN'S SUPREME LEADER CALLS MISSILE STRIKE AT BASES A 'SLAP IN THE FACE,' WARNS IT'S NOT ENOUGH

"And Iran is now staying within those red lines," Thiessen added. "We just saw their response. They were very careful."

Trump declared Wednesday that Iran “appears to be standing down” in the wake of missile strikes on Iraqi airbases that house American service members that the president said resulted in “no casualties.” For his part, Khamenei said Wednesday that the missile attacks were meant as "a slap in the face" to the United States.

"Trump gave a Reagan-esque speech today because he took Reagan-esque action. Words without action don't matter," Thiessen said. "When he took out Soleimani, the first thing I thought about was the fact that in 1986, Ronald Reagan drew a red line with [Libyan dictator] Colonel [Muammar] Qaddafi is that if you kill a single American, we're gonna come after your regime. And Qaddafi bombed a discotheque in West Berlin, killing American servicemen, and ... Ronald Reagan launched a decapitation strike against Qaddafi."

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Thiessen went on to urge Trump to "maintain deterrence" with Iran.

"The lesson from Ronald Reagan is that one strike, however bold, however courageous it was and it was, is not enough to deter them," Thiessen said. "What the Iranians want is the Iranians want us out of Iraq. They want us out of Syria. They want us out of the Middle East. And that's their long game."

"President Trump needs to understand he can't he can't give the Iranians what they want," Thiessen added. "He needs to maintain deterrence if he's going to have peace through strength."

Fox News' Frank Miles and Brooke Singman contributed this report.