North Korea has shifted a missile with "considerable range" to its east coast, South Korea's foreign minister says.
Kim Kwan-jin played down concerns that the missile could target the US mainland, and said the North's intentions were not yet clear.
Pyongyang earlier renewed threats of a nuclear strike against the US, though its missiles are not believed to be capable of carrying nuclear warheads.
The US is responding to North Korea by moving missile defence shields to Guam.
The Pentagon said the shield on its Pacific island territory would be ready within weeks, adding to warships already sent to the area.
The North has previously named Guam among a list of possible targets for attack that included Hawaii and the US mainland.
Japanese and South Korea reports had suggested the missile being moved by the North was a long-range one with a capability of hitting the US west coast.
However, experts believe the North's most powerful rocket, which it test-fired last December, has a range of 6,000km (3,700 miles) and can reach no further that Alaska.
Kim Kwan-jin told MPs in a parliamentary defence committee meeting that the missile had "considerable range".
"The missile does not seem to be aimed at the US mainland. It could be aimed at test firing or military drills," he said.
Analysts have interpreted Mr Kim's description as referring to the Musudan missile, estimated to have a range up to 4,000km. Guam would be within that range.
The North is believed to have its main military research centres in the east.
It has test-fired missiles from there before, and its three nuclear-weapons tests were carried out in the east.
But in recent weeks it has threatened nuclear strikes and attacks on specific targets in the US and South Korea.
It has announced a formal declaration of war on the South, and pledged to reopen a mothballed nuclear reactor in defiance of UN Security Council resolutions.
In its latest statement, attributed to a military spokesman, the North appeared to refer to ongoing military exercises between the US and South Korea in which the US has flown nuclear-capable bombers over the South.
The statement said the "ever-escalating US hostile policy towards the DPRK [North Korea] and its reckless nuclear threat will be smashed".
It promised to use "cutting-edge smaller, lighter and diversified nuclear strike means of the DPRK" and said the "merciless operation of its revolutionary armed forces in this regard has been finally examined and ratified".
The US Department of Defense said on Wednesday it would deploy the ballistic Terminal High Altitude Area Defense System (Thaad) to Guam in the coming weeks.
The Thaad system includes a truck-mounted launcher and interceptor missiles.
US officials recently also announced that the USS John McCain, a destroyer capable of intercepting missiles, had been positioned off the Korean peninsula.
Some analysts say Pyongyang's angry statements are of more concern than usual because it is unclear exactly what the North hopes to achieve.
As well as the rhetoric, Pyongyang has also taken action to deepen antipathy with the South.
It has shut down an emergency telephone line and stopped giving access to South Koreans who work at the joint industrial zone in Kaesong in the North.
The Kaesong complex is staffed mainly by North Koreans but funded and managed by South Korean firms.
Pyongyang blocked access for a second day on Thursday, and threatened to shut down the zone. [
Source]
