The Pentagon abruptly ordered an aircraft carrier on its way home from the Middle East to turn around as it warned Iran

• Acting Secretary of Defense Christopher Miller on Sunday abruptly ordered an aircraft carrier on its way home to change course and return to the Middle East as a warning to Iran.
• He said the move was in response to Iranian threats against the president and other government officials.
• The unexpected order, which reportedly came from President Donald Trump, came after a flurry of US military activity in the area in the final weeks of the Trump administration.

The Pentagon on Monday unexpectedly ordered an aircraft carrier that was on its way home to turn around and head back to the Middle East to deter Iran.

Acting Secretary of Defense Christopher Miller announced on Thursday that the US Navy nuclear-powered aircraft carrier USS Nimitz was returning to its home port to wrap up a lengthy 10-month deployment.

On Sunday evening, he announced that he ordered the Nimitz to "halt its routine redeployment," saying the carrier would "now remain on station" in the Middle East. The move, Miller said, is a response to "recent threats issued by Iranian leaders against President Trump and other US government officials."

"No one should doubt the resolve of the United States of America," he said in his statement.

Miller's earlier decision to send the aircraft carrier home, a decision that went against the advice of senior military advisors, was intended to de-escalate tensions with Iran.

But President Donald Trump directed Miller on Sunday to send the carrier back to the Middle East, CNN reported Monday.

Trump threatened Iran on Twitter after a large rocket attack on the US Embassy in Baghdad by Iranian-backed militia forces toward the end of December. Writing that there had been "chatter" of more attacks, he said: "If one American is killed, I will hold Iran responsible."

Sunday marked the first anniversary of the US drone strike that killed Iranian Maj. Gen. Qassem Soleimani, a prominent Islamic Revolutionary Guard Corps commander, and Abu Mahdi al-Muhandis, an Iranian-backed militia leader in Iraq. That airstrike was carried out in response to a rocket attack that killed a US citizen, among other considerations.

Soleimani's death led Iran to unleash a barrage of ballistic missiles on US and coalition forces in Iraq a few days later. In the weeks leading up to the first anniversary of the general's death, there had been some concern that Iran might act aggressively.

Ahead of the anniversary, there was a flurry of US military activity in the region.

The US military sent B-52H Stratofortress bombers on deterrence flights through the Persian Gulf three times from late November to late December.

Gen. Frank McKenzie, the US Central Command commander, said at the time of the second flight on December 10 that "potential adversaries should understand that no nation on earth is more ready and capable of rapidly deploying additional combat power in the face of any aggression."

Commenting on the B-52 bomber flights, a senior military official told NBC News that tensions with Iran were running high.

"We want to ensure that if they are contemplating some sort of an aggressive act, that they would they would think twice about it before they did it," the official said.

On December 21, the Navy announced the presence of the guided-missile submarine USS Georgia and the guided-missile cruisers USS Port Royal and USS Philippine Sea in the Persian Gulf.

The rare statement, the first in eight years to announce that a guided-missile submarine was in the Persian Gulf, emphasized the submarine's combat capabilities, specifically the 154 Tomahawk land-attack cruise missiles on board.

The Navy said in its statement that USS Georgia's "presence demonstrates the United States' commitment to regional partners and maritime security with a full spectrum of capabilities to remain ready to defend against any threat at any time."