Enraged North Korean leader Kim Jong-un is alleged to have ordered terror attacks against top South Korean nationals living in China and other East Asian nations over the defection of a London-based diplomat. The step is believed to be part of a series of harsh measures, including abductions that Kim has taken following Thae Yong-ho's defection to South Korea along with his family.

Security for South Koreans living abroad has been stepped up due to the perceived threat, given that the high-profile defection has caused a huge embarrassment to Kim's regime.

A top source told South Korean news agency Yonhap that there have been several indications that Pyongyang could be trying to harm South Korean citizens as retaliation. "I can't give out the full details but the North Korean leadership has been infuriated over the series of recent incidents. For North Korea, provocative acts that won't leave any trace will be the easiest, like hiring local gangsters to commit a terrorist attack," the source said. South Koreans travelling to border areas between China and North Korea have also been asked to stay alert.

In a dramatic move, Thae fled to South Korea from London last week as he got "tired of Kim Jong-un's regime". Following the high-profile incident, Pyongyang said in its first response that Thae was a "criminal". The state-run Korean Central News Agency said in a dispatch that Thae "was instructed to return home in June last for questioning as regards the embezzlement of huge amount of state funds, leakage of state secrets for money and rape of a minor".

Meanwhile, Pyongyang has heaped scorn over South Korea's decision to hold its largest-ever artillery drill in the volatile border region known as the demilitarised zone (DMZ). On 21 August, Uriminzokkiri, the North's main online-based mouthpiece, wrote: "In the past, (South Korea) has been crazy about military provocations driven by a war fever to invade North Korea, but the latest shelling exercise which involved so many artillery units lurking along the front-line is unprecedented." The report claimed that the drill threatens the peace and stability of the Korean peninsula.

There has been a war of words and defiant acts from the rival Koreas in recent weeks raising fresh tensions.