Amidst an increasing threat of a nuclear war from North Korea, Japan is reportedly planning a possible evacuation of its citizens from South Korea, which is just a few hundred kilometres away from North's Pyongyang.

"There is a possibility of further provocations. We need to remain extremely vigilant and do everything we can to ensure the safety of our people," Japanese Prime Minister Shinzo Abe said on Monday, according to Japanese magazine Nikkei Asian Review. 

Japan has also been conducting evacuation drills in its small coastal town on the Sea of Japan — the region was warned of a ballistic missile attack — amidst tensions with North Korea's burgeoning missile and nuclear programme. Hundreds of residents of Abu were rushed to safety as part of the evacuation drill.

The authorities had also recently sent text messages to the residents issuing an alert to evacuate their homes after a North Korea missile crossed the region. 

Japanese Prime Minister Shinzo Abe
Japanese Prime Minister Shinzo AbeReuters

North Korea on Sunday claimed it had successfully detonated a hydrogen bomb, which possible triggered a 6.3-magnitude artificial earthquake. 

Reports state nearly 60,000 Japanese citizens reside in South Korea at the moment, and there are about 38,000 long-term residents among them, while roughly 19,000 are tourists or short-term visitors.

"If the US decided on a military strike against the North, the Japanese government would start moving toward an evacuation on its own accord regardless of whether the American plans are public," a Japanese government source told the Nikkei Review, according to Fox News reports.

Japan evacuation drill
School students participate in an evacuation drill in JapanReuters

Japan's plan of evacuation reportedly consists of four steps that include limiting unnecessary travel of its citizens to South Korea, discouraging all nature of travel to the South, advising Japanese citizens to evacuate, and encouraging them to find shelter in a secured place.

South Korea has began conducting live-fire training exercise in a show of force, simulating an attack on a nuclear site in North after Pyongyang's hydrogen bomb test.

This was North Korea's sixth such test, after the Kim Jong-Un ruled nation received incessant warnings and tough sanctions from the United Nations, in an effort to curb North's nuclear programme.