Fresh satellite images show increasing activity at North Korea’s launch site, an indication that it could be ready to fire a long-range rocket within several weeks, South Korean officials said Tuesday.

“There is a high possibility” of a launch in December or January, a senior military official told South Korea’s Yonhap news agency.

The assessment followed the release of an image Monday by DigitalGlobe, which provides satellite imagery to the U.S. government. The image showed people, trucks and fuel tanks at the Sohae launch site, in North Korea’s northwestern corner. The activity, DigitalGlobe said on its Web site, is consistent with preparations in the weeks before Pyongyang’s attempt to launch a long-range missile in April.

The family-run police state has said nothing about imminent plans for a launch, and security analysts cautioned that Pyongyang might not go through with a move that would rile its lone benefactor, China, whose Communist Party is breaking in new leadership.

But a North Korean delegate told a U.N. General Assembly meeting two weeks ago that the North would expand its space development program and “go through with launches of working satellites of all kinds essential for the economic development of the country.”

North Korea has claimed that previous rocket launches were used to place satellites into orbit. Washington and its allies in East Asia, however, say that such launches are de facto long-range missile tests, because they rely on the same technology. The North is banned under U.N. security resolutions from using “ballistic missile technology.”

If the North does proceed with a launch, timing will be crucial: It could become either a factor in South Korea’s Dec. 19 presidential election or the first major test for the new leader.

For now, North Korea lags far behind the economy as a top concern for South Korean voters. Although both presidential contenders favor a softer approach to the North, liberal candidate Moon Jae-in wants to restore the joint economic projects that were scrapped under the current president, Lee Myung-bak. Moon also has said he will seek summit talks next year.

North Korea has tried and failed three times to send a satellite into orbit, most recently on April 13, when the Unha-3 rocket fell apart shortly after launch. The launch had been intended as the showcase moment of a weekend celebrating the 100th birthday of deceased national founder Kim Il Sung.

The North is gearing up for another anniversary Dec. 17, which marks one year since the death of Kim Jong Il, who is Kim Il Sung’s son and the father of current supreme leader Kim Jong Eun.