North Korea's Deputy Foreign Minister Han Song-ryol told the BBC that an "all out war" could result if the US took military action. "We'll be conducting more missile tests on a weekly, monthly and yearly basis," Han said in Monday's interview.

His comments came a day after the country test-fired a missile, which exploded within moments of its launch. The malfunctioning missile was intended to be part of the celebrations commemorating the 105th anniversary of the birth of Kim Il-sung, the country's founding president and "eternal president."

Nuclear weapon 'not a bargaining tool'

Another North Korean deputy foreign minister, Sin Hong-chol, meanwhile told Al Jazeera news that its army was on "maximum alert" after Monday's visit by US Vice President Mike Pence to the Korean Demilitarized Zone (DMZ) between South Korea and the North. There, Pence had said that Washington's "era of strategic patience" with regard to North Korea was over.

Sin warned that "if we notice any sign of assault on our sovereignty, our army will launch merciless military strikes against the US aggressors, wherever they may exist, from the remote US lands to the American military bases on the Korean Peninsula, such as those of Japan and elsewhere."

"The nuclear weapon in our possession is not illusion; it is not a commodity that may be traded for American dollars - nor is it for sale. So it cannot be put on the negotiating table with the aim to rip it off," Sin said in the interview with Al Jazeera.

North Korea threatens with retaliation if attacked

North Korean Deputy Ambassador to the United Nations Kim In Ryong meanwhile told a news confernece in New York that the hermit kingdom was ready for "any mode of war," saying that North Korea would respond to a missile or nuclear strike "in kind."

"If the United States dares opt for a military action (...) the DPRK is ready to react to any mode of war desired by the Americans," Kim said. "We will take the toughest counteraction against the provocateurs."

US remains tough against North Korea

The statements from the North Korean envoys came after US Vice President Mike Pence told Pyongyang not to test US resolve following the failed missile test.

"All options are on the table as we continue to stand shoulder to shoulder with the people of South Korea," Pence said during his visit to the Korean Peninsula after US President Donald Trump had sent a Navy strike group to the Korean peninsula earlier in the weekend.

Russia also reacted to Pence's comments on the Koreas' border, with Foreign Minister Sergei Lavrov telling reporters in Moscow: "I hope very much that there will not be any unilateral steps as we did in Syria." 

Meanwhile US Secretary of State Rex Tillerson is planning to chair a special meeting of the UN Security Council on North Korea next week.