Russia on Thursday strongly condemned North Korea's actions in the intensifying standoff with South Korea and the United States, saying Pyongyang was showing a "categorically unacceptable" contempt of UN resolutions.

"For Russia, Pyongyang's neglect of UN resolutions (on nuclear non-proliferation) is categorically unacceptable," foreign ministry spokesman Alexander Lukashevich told reporters.

His comments were Russia's sharpest criticism of Pyongyang in the current crisis. Until now, Moscow had urged restraint from all parties and warned that the general situation risked escalating out of control.

Lukashevich said North Korea's actions "complicate, if not practically rule out the chances of resuming" the suspended six party talks including world and Asian powers to ease tensions on the Korean peninsula.

Pyongyang has threatened missile and nuclear strikes against the United States and its ally South Korea in response to UN sanctions and joint military drills.

Lukashevich appeared to also take Pyongyang to task over its increasingly bellicose rhetoric.

"Our main thesis is to as soon as possible stop these dangerous manoeuvres and rhetoric and create conditions for restoring as soon as possible the six-party talks process."

"We remain convinced that all these measures and warlike statements are absolutely categorically unacceptable," Lukashevich said, describing the situation as "extremely tense".

Russia shares a short border with North Korea south of Vladivostok in its Far Eastern region and retains relatively close ties with the secretive Stalinist state.

UN chief tells N.Korea to rein in nuclear threats
Madrid (AFP) April 04, 2013 - UN Secretary General Ban Ki-moon told North Korea on Thursday to rein in its nuclear threats, warning that any miscalculation could lead to an extremely grave outcome.

North Korea has issued a crescendo of nuclear threats over past weeks, culminating in a military statement Thursday that it had received approval for action possibly including nuclear strikes.

The daily security and humanitarian reports from Pyongyang are "really alarming and troubling", the United Nations chief told a news conference in Madrid.

"Nuclear threat is not a game, it is very serious," Ban told reporters after meeting with Spanish Prime Minister Mariano Rajoy.

"I think they have gone too far in their rhetoric and I am concerned that if by any misjudgement, by any miscalculations ... this will have very serious implications," the UN boss said.

Ban, a former South Korean foreign minister, said he had been repeatedly appealing to Pyongyang to reduce tensions and engage "proactively and constructively" for peace and security on the Korean peninsula.

He called on all parties to work together to ease tensions and open dialogue.

South Korea said the North had moved a medium-range missile to its east coast as the United States strengthened its Pacific missile defences amid the intensifying threats from Pyongyang.

Seoul's defence minister Kim Kwan-Jin said the missile could reach a "considerable distance" but not the US mainland.

"It could be aimed at test-firing or military drills," he told lawmakers Thursday.

Earlier in the day, North Korea's general staff, angered by UN sanctions and South Korea-US military drills, issued a statement saying: "The moment of explosion is approaching fast".

It said the US use of nuclear-capable B-52 and B-2 stealth bombers in war games with South Korea was provocative.

The US aggression would be "smashed by... cutting-edge smaller, lighter and diversified nuclear strike means," it said.

The Pentagon said it would send ground-based THAAD missile-interceptor batteries to protect bases on Guam, a US territory some 3,380 kilometres (2,100 miles) southeast of North Korea and home to 6,000 American military personnel.

Military balance on the Korean peninsula
Seoul (AFP) April 4, 2013 - After North Korea announced Thursday it has approved plans for nuclear strikes on US targets, here are some facts on the relative conventional strengths of the three militaries present on the Korean peninsula.

The figures are taken from the London-based International Institute of Strategic Studies' annual global "Military Balance" report, 2011.

North Korea's annual defence spending as of 2008 was estimated at $8.2 billion, or 22-24 percent of GDP, while South Korea's as of 2012 was $30.8 billion, or 2.7 percent of GDP.

South Korea is protected by the US "nuclear" umbrella, while North Korea, which conducted its third nuclear test in February, claims a potent nuclear weapons capability.

The range of North Korean missiles, and its ability to manufacture and deliver working nuclear warheads, are a matter of dispute.

Most experts think it is not yet capable of mounting a nuclear device on a ballistic missile capable of striking US bases or territory.

                            North Korea          South Korea (+ US forces)

GROUND FORCES

   Active troops                  1.2 million          655,000 (+ 28,000)
   Reserves/Paramilitaries        5-7.7 million        3.0 million
   Tanks                          4,100                2,400 (+ 50)
   Armoured personnel carriers    2,500                2,600 (+ 110)
   Field artillery pieces         8,500                5,200 (+ 16)
   Multiple rocket launchers      5,100                200 (+ 40)
   Mortars                        7,500                6,000
   Air Defence Guns               11,000               300

AIR FORCES

   Combat aircraft                820 (620 serviceable) 460 (+ 90)
   Helicopters                    300                   680 (+ 120)

NAVAL FORCES

   Principal combat vessels       3                     19 
   Patrol and coastal vessels     383                   111
   Submarines                     70                    23
   Hovercraft                     135                   5
   Landing ships and craft        130                   41