An increasingly credible North Korean nuclear threat

South Koreans watching a news programme regarding the test-firing of a missile by North Korea, at a train station in Seoul on Feb 12, 2017. PHOTO: EPA

SINGAPORE - A tweet sent out by Mr Donald Trump on Dec 13, 2012, is now making its rounds following North Korea's latest missile launch.

"We can't even stop the Norks from blasting a missile. China is laughing at us. It is really sad," he tweeted.

Just a day earlier, on Dec 12, 2012, Pyongyang launched a long-range Unha-3 three-stage rocket, successfully putting a satellite into orbit.

Mr Trump, now the US president, may have reason to feel sad again.

On Sunday (Feb 12), North Korea fired its first ballistic missile for the year, and the first since Mr Trump was elected president in November.

While the latest missile is a mid-range missile, experts warn that Pyongyang is getting closer in its quest to build an inter-continental ballistic missile (ICBM).

Its launch of a rocket in 2012, for instance, uses technology very similar to that of a long-range missile.

Arms control experts warn that North Korean scientists can learn a lot with each missile or satellite launch, whether or not it is successful. After all, the same basic technology is involved for satellite launches and ballistic missile development.

"The bottom line is that North Korea is developing the technology it could use to build a ballistic missile with intercontinental range," wrote missile expert David Wright, a senior scientist at the Massachusetts-based Union of Concerned Scientists, in a blog post last year.

North Korea has been making strides towards its declared goal of developing an intercontinental ballistic missile capable of carrying nuclear warheads to strike the US mainland. And its missile and nuclear programmes has gathered pace in recent years, particularly after leader Kim Jong Un officially took power in 2012.

Since 2006, it has conducted five nuclear tests, two within the space of eight months - in January and September 2016.

In March 2016, North Korea released photographs supposedly showing its leader Kim Jong Un visiting a facility that manufactures miniaturised nuclear warheads which can fit on a ballistic missile.

In that same month, North Korea announced it has conducted a successful test of a heat shield for a re-entry vehicle.

In April 2016, North Korea announced it had tested a new type of ICBM engine.

In December 2016, a senior US military official told reporters on condition of anonymity: "I think they could mate a warhead with a delivery device. They're just not sure (about) re-entry."

Re-entry refers to the technology that allows a warhead to re-enter the Earth's atmosphere without breaking up.

Professor Kim Dong Yup who is with Kyungnam University's Far East Institute told news website NK News that Pyongyang already has re-entry technology for short-range missiles, but not for ICBMs.

The intelligence community estimates suggested that North Korea could eventually achieve re-entry capability in three to five years, said Mr Scott A. Snyder, Senior Fellow for Korea Studies and Director of the Program on U.S.-Korea Policy, Council on Foreign Relations, during a recent podcast.

In his televised New Year message on Jan 1, 2017, North Korean leader Kim Jong Un boasted that Pyongyang was in the "final stages" of developing an ICBM, a claim no longer dismissed by nuclear experts.

In response to Mr Kim's New Year message, then president-elect Trump tweeted, "It won't happen!"

On Sunday (Feb 12), US and South Korean officials quickly ruled out the possibility that it was an ICBM, based on the flight distance.

It was more likely a mid-range Rodong (also known as Nodong) missile, said South Korea's Joint Chiefs of Staff (JCS) in their initial assessment on Sunday but later said it was a "modified intermediate-range Musudan ballistic missile possibly equipped with a solid fuel engine".

North Korea's Rodong Sinmun has since provided pictures of what it is calling the "Pukguksong-2, solid-fuel missile". The pictures show something very similar to the KN-11 solid-fuel submarine-launched missile successfully tested in August 2016, which North Korea calls the Pukguksong-1.

Website 38 North, an authoritative source of information on North Korea's missile programme, said the new missile "does not need to be fuelled prior to launch, it can launch on perhaps five minutes' notice compared to the thirty to sixty minutes required for a Nodong".

"All of these factors would make it much harder to find and preemptively destroy the Pukguksong-2," wrote Dr John Schilling on the website.

North Korea has never successfully tested an ICBM despite displaying the KN-08 and KN-14 missiles at military parades.

But some analysts thought the launch could have been the first stages of an ICBM.

Dr Jeffrey Lewis of the Center for Non-proliferation Studies at the Middlebury Institute of International Studies told The Washington Post: "They finished testing that engine on the stand so now it's time to test it in the air."

The development of the solid-fuel intercontinental ballistic missile, which is easy to move and launch, has started, Prof Kim told NK News.

Mr Cheong Seong Chang, senior fellow at the Seoul-based Sejong Institute, says North Korea is expected to rapidly advance its nuclear and ICBM programme until South Korea's presidential election, which will be held in May at the earliest.

Given Pyongyang's long-honoured tradition of timing missile and nuclear tests to mark key anniversaries, North Korean watchers are betting on April as the likely window for its next missile or nuclear test - if not its first ICBM test.

Sunday's launch is also conducted four days ahead of the Feb 16 birthday of its late leader Kim Jong Il.

In April, the reclusive regime celebrates not one but three key events: founder Kim Il Sung's 105th birthday on April 15; Kim Jong Un's 5th anniversary as the Chairman of the ruling Workers' Party of Korea on April 11; and Kim Jong Un's 5th anniversary being anointed the supreme leader of North Korea on April 13.

That's just two months away.

This story was updated on Feb 14, 2017.

Join ST's Telegram channel and get the latest breaking news delivered to you.