Shortly after tweeting the US military was “locked and loaded” should North Korea “act unwisely,” President Donald Trump returned to Twitter on Friday to emphasize his point by retweeting images of US B-1 bombers currently stationed in Guam.

Featuring a series of photos depicting B-1B Lancers deployed to the US territory, the tweet from US Pacific Command said: “B-1B Lancer #bombers on Guam stand ready to fulfill USFK’s #FightTonight mission if called upon to do so.”

A key part of the US military’s “tip of the spear,” US B-1 bombers have been seen regularly over the Korean Peninsula in recent months amid escalating tensions with Pyongyang — running regular training flights with Japanese and South Korean fighter jets that often provoke the ire of the North Korean regime.

On Tuesday, Trump warned Pyongyang not to make any more threats against the United States or they will “face fire and fury like the world has never seen.”

Soon after Trump’s comments, North Korea issued a statement saying it was “examining the operational plan” to strike areas around the US territory of Guam in the Pacific, including the Andersen Air Force base where the US B-1 bombers are stationed.

While it was released Wednesday, the statement was dated Tuesday and didn’t make any reference to Trump’s comments. It did, however, express anger over a US flyby of B-1B bombers on Monday.

Another statement was issued by North Korean state media Wednesday warning the US that a “preemptive strike is no longer the monopoly of the US.”

The highly versatile, supersonic B-1 is considered the backbone of the US long range bomber fleet and carries the largest conventional payload of any aircraft in the US Air Force.

The US is currently rotating six B-1s through Andersen Air Force Base in Guam which would serve as a key aerial assets should Trump order a military strike on North Korea either preemptively or as a quick response to escalation from Pyongyang.

While the US would likely use stealth aircraft such as the F-22s, F-35s and B-2 bombers to lead an initial strike targeting North Korean air defense systems, B-1s would likely be dispatched from Guam once those defensive capabilities were disabled — utilizing its heavy payload to strike North Korea’s fortified nuclear weapons sites, according to Carl Schuster, a former director of operations at the US Pacific Command’s Joint Intelligence Center.

Launching a devastating preemptive strike against North Korea is almost unanimously considered a last resort for the US and analysts said there are currently no signs that the US is planning a first strike.

The US would surely use military force in response to any North Korean strike against American or allied targets, but two US defense officials told CNN on Thursday that there are no signs of any imminent launch activity from the rogue state.

But the concept of preemptive military action is, at very least, being considered as an option as Trump remains committed to keeping “all options on the table” amid tensions with Pyongyang.

Claims that Pyongyang is considering a missile strike near Guam, coupled with Trump’s warning “military solutions are now fully in place, locked and loaded, should North Korea act unwisely,” have fueled concerns of a potential conflict.

On Thursday, North Korean state media KCNA said military leaders were working on a proposal to launch four intermediate-range Hwasong-12 missiles into the sea less than 25 miles off Guam’s coast.

KCNA said the plan would presented to Kim by mid-August.

Guam’s Homeland Security Advisor George Charfauros said Friday it would take 14 minutes for a missile fired from North Korea to reach Guam.

“It’s a 14-minute flight time if all the factors are successful and if it gets through all the US defense layers in place,” Charfauros told CNN. North Korea had previously said the flight time would be 1,065 seconds, or just under 18 minutes.

On Thursday, Trump replied to North Korea’s threat to hit Guam with a threat of his own.

“Let’s see what he does with Guam,” Trump said in apparent reference to Kim. “He does something in Guam, it will be an event the likes of which nobody has seen before.”

“You’ll see, you’ll see. And he’ll see,” he said.