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PYONGYANG — North Korea is ready to test-fire an intercontinental ballistic missile “at any time, at any place,” according to a senior regime official speaking exclusively to NBC News.

If such a launch was successfully carried out, it would be a major step toward Pyongyang’s goal of targeting the U.S. mainland with a nuclear-armed weapon.

The comments were made by Choe Kang Il, deputy director general for North American affairs at North Korea’s foreign ministry, and highlight international concerns that Kim Jong Un's regime is more technologically advanced than previously thought.

Choe rejected the suggestion that any test launch would be provocative.

"Our measures to bolster our nuclear arsenal are all defensive in nature — to defend our sovereignty and to cope with the persistent nuclear blackmail and threats by the United States against our country," he said.

North Korea has conducted a total of five nuclear tests, including two last year, but the country has never successfully launched an ICBM.

The country regularly threatens nuclear attacks against the United States but, until 2016, analysts had thought the country was a long way from developing missile technology that would make them capable of doing so.

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However, North Korea has repeatedly threatened to test-fire an ICBM since its leader, Kim, said in his New Year message that the country’s preparations for such a test were at an advanced stage.

Some experts now assess that North Korea’s capabilities may have been underestimated.

“Pyongyang is much further along in their missile development than most people realize," said Melissa Hanham, a senior research associate at the U.S.-based Middlebury Institute of International Studies at Monterey, California, told Reuters earlier this month.

Choe claimed that North Korea viewed the regular joint U.S.-South Korean military exercises as a provocation that was spurring the regime to enhance its nuclear weapons capability.

Related: North Korea Warns It Would Use Nuclear Weapons First If Threatened

“Imagine if our troops went to Canada and Mexico to carry out a nuclear exercise aimed at invading the U.S., what kind of response would you expect from the American people?" he said. "As long as the U.S. conducts these joint military exercises we will increase our nuclear deterrent forces and our preemptive strike forces."

Asked about the only policy the President Donald Trump's administration had so far announced regarding North Korea — the establishment of a state-of-the-art anti-missile defense system to counter the threat from both that country and Iran, Choe said:

"It's a provocation. If the U.S. wants to develop the system, it should not use our country as an issue or an excuse. The U.S. is intentionally aggravating the tensions on the Korean peninsula in order to realize its ambition of dominating Asia."

North Korea just stated that it is in the final stages of developing a nuclear weapon capable of reaching parts of the U.S. It won't happen! — Donald J. Trump (@realDonaldTrump) January 2, 2017

He did, however, sound some conciliatory notes on relations with the U.S., saying: “Our supreme leader Kim Jong Un said even though it has been hostile to us in the past, if the U.S. becomes friendlier to us we will develop that relationship.”

Asked if he welcomed Trump's remark that he would be prepared to meet Kim, the official said "we will wait and see the difference between his campaign rhetoric and his policy as President."

Related: Analysis: What Will Trump Do About North Korea’s Kim Jong Un?

Speaking further about the U.S.'s new leader, Choe said: "We’re not worried who is president, but whoever is president should recognize that North Korea is a nuclear power and a military giant. We hope the new president will recognize that position and will drop America's hostile policy towards our country. He would be well advised to secure a new way of thinking."

North Korea’s nuclear activities have prompted the international community to impose a stringent sanctions regime on Pyongyang via the United Nations, targeting the country’s banking, travel and trade, as well as access to foreign-made military equipment.

"Sanctions aren't working. They will not stop our nuclear program," Choe told NBC News.

In January last year, Pyongyang offered to end its nuclear tests, in exchange for a peace treaty with the U.S. to formally end the 1950-53 Korean war and a halt to the annual U.S.-led military exercises in the region.

State Department officials said that the U.S. rejected the proposal, as the North Koreans refused to take steps to curb its nuclear arsenal.