Explainer: How cruise missiles differ from ballistic counterparts

North Korea tested its new long-range cruise missiles over the weekend, giving leader Kim Jong Un a unique alternative to bolster the armaments already at the isolated country's disposal.

This comes after its neighbour South Korea tested its submarine-launched ballistic missiles earlier this month, on top of developing other weapons that can rival nuclear warheads in destruction capabilities.

Here is a closer look at the two different types of missiles:

1. BALLISTIC MISSILES

These missiles are initially powered upwards by rockets, before following a free-falling trajectory towards their targets once their fuel is consumed.

They can be fired in varying distances by a configuration known as staging, that is by stacking rockets on top of one another in four different classifications:

• Short range (less than 1,000km)

• Medium range (1,000-3,000km)

• Intermediate range (3,000-5,500km)

• Intercontinental (More than 5,500km)

Ballistic missiles have three stages of flight - boost, mid-course, and terminal - that can take up to 25 minutes from launch until they hit their targets. Their trajectories take them into space or exoatmospheric heights before descending to Earth.

2. CRUISE MISSILES

These missiles are primarily propelled by jet engines and have a range of more than 1,000km.

Unlike ballistic missiles, cruise missiles remain close to the Earth's surface within the atmosphere during their flight. According to the Missile Defence Advocacy Alliance, this low flight path makes it harder for them to be detected by missile defence systems, but also means they use more fuel.

As they are self-guided, the cruise missiles can use methods including global positioning systems (GPS) and attached cameras to more accurately strike their target, or even be guided by remote operators to abort the strike.

A faster version of cruise missiles, known as a hypersonic missile, is being developed.

A version of this article appeared in the print edition of The Straits Times on September 14, 2021, with the headline 'Explainer: How cruise missiles differ from ballistic counterparts'. Subscribe