President Trump and Lindsey Graham got into a Twitter fight after the South Carolina senator said the commander in chief’s “measured” action to date on Iran showed “weakness.”

“The measured response by President @realDonaldTrump regarding the shooting down of an American drone was clearly seen by the Iranian regime as a sign of weakness,” Graham wrote, referring to an incident this summer in which the US planned a retaliatory strike but the president canceled it at the last minute.

That move emboldened Iran’s mullahs, Graham continued in another tweet, and encouraged aggression such as the drone and cruise missile attack on the Saudi oil industry, which the US has blamed on Iran, which denies the charge.

“The problems with Iran only get worse over time so it is imperative we take decisive action to deter further aggression by the Ayatollah and his henchman,” said Graham, referring to the US response to Saturday’s attacks.

The president fired back on Twitter, arguing that his restraint was actually a show of strength.

“No Lindsey, it was a sign of strength that some people just don’t understand!” he wrote.

Trump on Wednesday said he ordered Treasury Secretary Steve Mnuchin to impose more sanctions on the Islamic Republic.

But the president offered mixed messages on how else America would respond to the attacks.

On Sunday, he said the US was “locked and loaded,” suggesting a military response.

A day later, he said he would prefer a negotiated resolution to the crisis.

And he said Tuesday that he’d prefer to not meet with Iran’s President Hassan Rouhani after previously indicating that he was open to meeting him without preconditions.

But Iran put the kibosh on any talks.

During the primary season before the 2016, Graham emerged as one of Trump’s harshest critics from the right.

But once Trump won the election, Graham changed his tune, frequently defending and heaping praise on the president.

“I am like the happiest dude in America right now,” a beaming Graham gushed on “Fox & Friends.”

“We have got a president and a national security team that I’ve been dreaming of for eight years. I am all in. Keep it up, Donald,” Graham added. “I’m sure you’re watching.”