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New satellite imagery appears to show activity at the Yongbyon nuclear complex in North Korea, suggesting to some experts that they will once again be able to produce plutonium for more nuclear weapons. According to reports, intelligence satellites captured steam rising from the previously shuttered facility, indicating that the main nuclear reactor is being powered up and will soon be put back into operation.

Yongbyon was effectively shut down in 2008, but is believed to have produced the fuel used in two of North Korea's three nuclear tests. Earlier this year, the government announced they would restart the facility in response to what it claimed were provocations by South Korea and the United States.

According to Reuters, the new activity isn't so much a threat as it is a reminder from Pyongyang that they are still around and still capable of nuclear mischief. (Even if the reactor is restarted, it would still take several years before it could produce enough material for nuclear weapons.) Most of the first half of 2013 was spent in very public feuding between North Korea and its enemies, with numerous threats of violence coming from North and calls for more sanctions coming from the United States. Now that the Obama administration is embroiled in the diplomatic fight over Syria, perhaps Kim Jong-un decided now would be a good time to quietly re-start work on his country's bid to be a legitimate nuclear power.

It's also the first sign of trouble after several weeks of what appeared to improving relations between the North and the South. Just this week, the two sides agreed to re-open the Kaesong industrial complex, the jointly-owned factory city that the North hastily shut down back in April. More than 50,000 North Korea workers are employed there, in factories that are (mostly) owned and managed by South Korean companies.

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