Kim Yong Nam, second to North Korean leader Kim Jong Il, also suggested Pyongyang was ready to return to the stalled six-party talks if sanctions against his country were lifted, Japan's Kyodo News agency reported from Pyongyang.
The new remarks came after North Korea shocked the world on Monday by claiming to have conducted its first nuclear bomb test, triggering a US-backed campaign to have the UNSC sanction the country.
"The issue of future nuclear tests is linked to US policy toward our country," Kim was quoted as saying when asked whether Pyongyang will conduct more nuclear tests.
"If the United States continues to take a hostile attitude and apply pressure on us in various forms, we will have no choice but to take physical steps to deal with that," he said.
Tensions heated up throughout North-East Asia today with South Korea's military reportedly readying for nuclear conflict and North Korea warning that an international push for tighter sanctions would be an act of war.
A North Korean official said that the isolated, impoverished nation would regard full-scale sanctions against it as a call to war, Yonhap news agency had reported.
