Hundreds of thousands of North Koreans rallied Friday in the freezing cold to revel in the country's rocket launch as South Korea voiced concern that its rival could follow up with a third nuclear test. The enormous rally in central Pyongyang came two days after the launch of the rocket and just ahead of Monday's anniversary of the death of new leader Kim Jong-Un's father. The West fears the launch has taken the nuclear power a step closer to firing intercontinental ballistic missiles across the planet, and it has provoked UN Security Council condemnation along with calls for more sanctions. North Korea is already under international sanctions for conducting two nuclear tests in 2006 and 2009, which both came after long-range rocket launches, and South Korea said history could be repeating itself. "A nuclear test is highly probable, and judging from analysis of intelligence, significant preparations have been made," Unification Minister Yu Woo-Ik told a parliamentary committee in Seoul, without elaborating. "North Korea has a track record of conducting nuclear tests following missile launches whose aim was to develop a delivery system for nuclear warheads," he added. Refuelling its criticism of Wednesday's launch, the US State Department said Kim had the chance as new leader "to take his country back into the 21st century" but instead was making the "wrong choices". Unbowed, North Korean state media said Kim, who is in his late 20s, had personally signed off on firing the three-stage rocket and had declared his regime's "unshakable stand" that the programme will continue. Kim stressed the need "to launch satellites in the future... to develop the country's science, technology and economy", according to the North's official Korean Central News Agency (KCNA) as it gave new details of the launch. The "dear respected Marshal" visited mission control an hour before the rocket took off on Wednesday morning and praised the "ardent loyalty and patriotic devotion" of the technical team, KCNA said in the report early Friday. The report gave no reaction to the international opprobrium that has been heaped on North Korea since the rocket went up, ostensibly to place a research satellite in orbit, with even close ally China expressing its "regrets". While again calling on North Korea to obey UN resolutions, Beijing's foreign ministry reiterated its stance that any action by the international community "should be prudent and measured" so as to preserve peace and stability. China, keeping a wary eye on the US military presence in South Korea, has defended North Korea's right to a peaceful space programme and kept a measure of ambiguity in its responses to the rocket launch by its erratic ally. However, a new nuclear test by Pyongyang would be an unambiguous menace to China's attempts to keep a lid on the situation on its northeastern border and make it harder for Beijing to impose restraint at the UN Security Council. While the United States and allies ponder their next moves, Friday's rally was an emphatic demonstration of organised support for the Kim dynasty within North Korea, one of the world's most tightly controlled states. Under a slate-grey winter sky, the massed ranks of civilians and soldiers were assembled into columns and proclaimed their obeisance to the younger Kim under giant portraits of his father and grandfather, chanting "long live!". Many of the civilians were in thin coats against the cold, and the soldiers in olive-green greatcoats and Russian-style trappers' hats, as they pumped their fists in unison, state television showed. Addressing the crowd on Kim Il-Sung Square, senior officials lavished praise on the Kim dynasty and its scion for the rocket launch -- which came after an April attempt ended in fiery failure. Analysts say the launch's symbolism was a prime motivating factor for North Korea as Kim shores up his leadership credentials. "The launch means the fulfilment of Kim Jong-Il's last wish," said Yoo Ho-Yeol, a political science professor at Korea University in Seoul. "As such, it helps cement Jong-Un's grip on power and strengthens his authority over the North's military elites, securing their loyalty and a sense of solidarity under his leadership," he said.