Relatives of US servicemen have rehearsed plans to evacuate South Korea as fears over North Korea's nuclear weapons program continue to mount.

Dependants of military personnel, and American civilians living in the East Asian nation, gathered recently at Yongsan Garrison in the capital Seoul to enact an emergency scenario should the North launch an attack.

The process sees US civilians register at the military base and receive instructions on how to fit an protective devices which guard against the effects of biological attacks for up to 12 hours.

US civilians on a plane bound for the Japanese island of Okinawa

Smiles: Alannah Martinez after she has been fitted in the ICAP costume

The volunteers were then transported by coach to Pyeongtaek, an hour to the south, where there were two Chinook helicopters waiting to take then to the city of Daegu -where they spent the night in barracks.

In the morning they went by coach to Gimhae Republic of Korea Air Force where they boarded a US military plane to Okinawa in Japan.

If the emergency were real they would then be flown to the US to complete the escape, but after the rehearsal they instead returned to South Korea.

The latest practice evacuation, which is set on the pretense that North Korea had launched a nuclear attack on Seoul, was attended by the Martinez family whose are stationed in the South.

Residents of South Korea have to register at the Yongsan Base in Seoul and are fitted with ICAP masks before making their way to Japan

Families receive instructions at the base as the exercise begins

Nicholle Martinez's husband, Nick, was given a posting with the US Army on the peninsula.

The couple's two daughters Briannah, 6, and Alannah, 8, took part in the whole process and the two girls even tried on the nuclear deterrent masks.

'In real life, everyone would be wearing masks, rushing through places,' Nicholle told CNN. 'There would be chaos everywhere. It would be scarier.

'We embrace these kinds of events because we help our spouses. My husband benefits from us enjoying our time here. If we're happy, he's happy.

'Knowing that I would be leaving my husband behind... that would be the hardest thing.'

Justin Sturn, a non-combatant evacuation planner, said threats from North Korea and leader Kim Jong-un's insistence on continuing the secluded country's nuclear regime have prompted the evacuation routines.

'With all the rhetoric that comes out of North Korea, of course we have to prepare for the worst case scenario.'

An military officer helps one of the girls into the anti-nuclear mask and suit

The Martinez family who are based in South Korea after Nick (left) was stationed on the peninsula

Colonel William Bell, 524th Military Intelligence Battalion S3 Operations Officer, said the safety of non-military personnel in the event of an attack is of paramount importance.

'The intent is to make sure that not only military personnel, but noncombatant evacuees as well, understand the procedures for evacuation, in order to make the process as smooth and quick as possible,' Col. Bell said.

In September, North Korea said it had tested its most powerful nuclear technology yet test amid international condemnation and aggressive sanctions which appear to have done little to impede the regime's nuclear ambitions.

In a New Year's address, Kim said that his country is close to testing an intercontinental ballistic missile.

The US military has had a strong presence in South Korea since fighting between the divided nations ended in 1953.