The US and South Korea have kicked off their two-week-long annual joint war drills as North Korea surprisingly fails to react over the manoeuvres.

The drills, called Ulchi Freedom Guardian (UFG), are aimed at gearing up the defence preparedness of both US and South Korean forces.

Nearly 50,000 South Korean troops and 27,000 US personnel in the Pacific region are to take part in the 12-day exercises. About 3,000 American troops have also been drafted from the US to participate in the drills. Although the war exercises are largely computer-aided, more than 80,000 soldiers are involved in order to strengthen the forces' defence capability.

The Combined Forces Command (CFC) said the drills will also ensure a working cooperation between the allies.

The simulations during the exercises will include intense defence drills against North Korea's provocations. The cyber wing of the troops will also be put under training to tackle potential threats from North Korea.

The drills will be closely monitored by representatives from the United Nations Command (UNC) states, namely the UK, Australia, Canada, Denmark, France, New Zealand and Norway.

Observers from the Neutral Nations Supervisory Commission (NNSC) will also be present to keep a close watch on the drills. The NNSC was established in 1953 as part of the Korean Armistice Agreement to ensure smooth implementation of the accord.

On the sidelines of the drills, the two sides will be involved in a four-day emergency exercise.

North Korea often dubs such exercises as war rehearsals but this time around, it has remained silent indicating the easing of tensions in the Korean Peninsula.

On the eve of the first day of the drills, North Korea agreed to hold talks with South Korea over reunion of families, separated since the 1950-53 Korean War. A South Korea-initiated dialogue is scheduled to take place in September.

The two Koreas have also reached an agreement to end the Kaesong complex standoff and are working towards reopening the industrial park.