North Korea said Wednesday it is contemplating a military strike that would create "an enveloping fire" around the U.S. Pacific territory of Guam, just hours after U.S. President Donald Trump vowed to counter threats from Pyongyang with "fire and fury."

Later Wednesday, however, U.S. Secretary of State Rex Tillerson told reporters he does not believe there is any "imminent threat" from North Korea and said, "Americans should sleep well at night, have no concerns about this particular rhetoric of the last few days."

North Korea's official media carried a statement from the Strategic Force of the Korean People's Army saying it is "carefully examining the operational plan for making an enveloping fire at the areas around Guam with medium-to-long-range strategic ballistic rocket Hwasong-12."

The plan aims to "contain" the U.S. military bases on Guam, including the Anderson Air Force Base at which U.S. strategic bombers are stationed, it said.

It said it will be "reported to the Supreme Command soon after going through full examination and completion and will be put into practice in a multi-concurrent and consecutive way any moment" once North Korean leader Kim Jong Un makes a decision.

The statement warned the United States to "immediately stop its reckless military provocation against" North Korea so that it "would not be forced to make an unavoidable military choice."

The strategic bombers' frequent visits to the skies above South Korea "get on the nerves" of North Korea, it said, which also criticizing an operational test by the U.S. Air Force of a Minuteman III intercontinental ballistic missile earlier this month.

Guam Gov. Eddie Calvo said Wednesday in a special address, "I want to reassure the people of Guam that currently, there is no threat to our island or the Marianas" that include Saipan, where a total of some 200,000 Americans reside.

He said there are "several levels of defense all strategically placed to protect our island and our nation," while the White House has given him assurances that Guam has Washington's full backing.

Speaking at his golf resort in Bedminster, New Jersey, on Tuesday, Trump said North Korea "best not make any more threats to the United States. They will be met with fire and fury and frankly power, the likes of which this world has never seen before."

Tillerson later said Trump, as commander in chief of the U.S. armed forces, was just reaffirming that "the United States has the capability to fully defend itself from any attack, and defend our allies, and we will do so."

Speaking before arriving in Guam, he said the president "felt it necessary to issue a very strong statement directly to North Korea."

In a separate statement from North Korea on Tuesday, also carried by the official Korean Central News Agency, a spokesman for the army general staff took issue with a remark by Trump's top security adviser over the weekend that the United States is preparing for a "preventive war" with North Korea.

The spokesman said any plans to execute this "will be countered with a just all-out war of wiping out all the strongholds of the enemies including the U.S. mainland," according to KCNA.

(Korea Media/Kyodo)