Speaking to CNN on Thursday, Dick Cheney said that concerns over North Korea's missile programme were being dealt with in the "proper fashion".
However, he said, the country should "come clean" about the extent of its intentions.
The news comes as both Russia and China urged all sides to return to the negotiating table after reports that North Korea was preparing to test fire a long range missile.
Cheney said: "This is not the kind of behaviour we'd like to see, given the fact the North Koreans do have a nuclear programme and have refused to come clean about it.
"They will obviously generate concern on the part of their neighbours and the US to the extent that they continue to operate this way."
Over the past few days there have been reports that North Korea, one of the world's most isolated countries, has been planning to test fire a new Taepodong-2 missile.
Experts estimate the missile's range could be up to 15,000km - making it capable of reaching parts of the US.
On Thursday the Russian government summoned North Korea's ambassador to explain the missile reports.
"It was stressed that any steps that could negatively impact regional stability and complicate the quest for a way to settle the nuclear problem ... were undesirable," Russia's foreign ministry said in a statement released following the meeting.
"You don't normally engage in conversations by threatening to launch intercontinental ballistic missiles"
US Ambassador to the UN
Meanwhile, China's foreign minister has urged all sides to solve the crisis through "negotiations and dialogue".
North Korea has said it wants talks with the US over its potential missile test, however the offer was starkly dismissed by the US ambassador to the UN, John Bolton.
"You don't normally engage in conversations by threatening to launch intercontinental ballistic missiles," he said on Wednesday.
The US wants discussions on North Korea's nuclear programme to be within the framework of six-party talks involving the two Koreas, the US, China, Japan and Russia.
Washington is calling for North Korea to return to the talks, which are stalled over a US crackdown on the North's alleged illicit financial activity.