SEOUL - A belligerent North Korea again sent tensions rising on the Korean peninsula with its latest missile launch that flew over Japan early on Friday (Sept 15).

It is the second missile it flew over Japan since it fired an intermediate-range missile over Japan on Aug 29.

North Korean leader Kim Jong Un said following the launch of the Hwasong-12 intermediate-range ballistic missile was a "meaningful prelude to containing Guam". There would be "more ballistic rocket launching drills with the Pacific as a target in the future", state media quoted him as saying. Friday's missile, which flew further than the Aug 29 missile, would far enough to reach Guam if fired in the direction of the US Pacific territory.

It was the 15th missile test by North Korea this year and the first since North Korea detonated its sixth and most powerful nuclear bomb to date on Sept. 3. Officials are still analysing the flight data to determine what type of missile was launched.

Japanese prime minister Shinzo Abe, who was visiting India this week, had earlier said the Aug 29 missile launch poses "an unprecedented, serious and a grave threat" to Japan.

So what does Kim really want to achieve with the seemingly endless string of missile tests? Analysts share their views.

TO HAVE DIRECT TALKS WITH THE US

Some experts said Kim Jong Un was trying to pressure Washington to the negotiating table with the latest tests.

"(North Korea) thinks that by exhibiting their capability, the path to dialogue will open," Masao Okonogi, professor emeritus at Japan's Keio University, said by phone from Seoul. "That logic, however, is not understood by the rest of the world, so it's not easy," he told Reuters.

In recent weeks, several US lawmakers have publicly supported the idea of engaging in diplomacy with North Korea - with some indicating a willingness to support direct talks with Pyongyang, reported CNN.

"The North Koreans have been wanting direct talks with the US for over a year but don't want to commit in advance to denuclearisation or to take steps unilaterally before talks begin," said Leon Sigal, Director of the Northeast Asia Cooperative Security Project at the Social Science Research Council.

According to Sigal, North Korea's desire to change its relationship with the US dates back more than 30 years, and their hopes of altering US policy they see as adversarial could provide leverage in attempts to bring Pyongyang to the table.

The Trump administration has repeatedly said that talks can take place on the pre-condition of denuclearisation.

But Adam Mount, a senior fellow at the Washington-based Center for American Progress, said: "If Trump and Tillerson believed North Korea backed down, they were sorely mistaken. "They're not going to volunteer to do this (give up their weapons). Ever," he said.

"It's a matter of bargaining. And North Korea has signalled over and over again that the price is really high."

TO ENSURE REGIME SURVIVAL

Analysts say North Korea believes developing a nuclear weapon that can fit atop a missile powerful enough to reach the United States is the only way Pyongyang can deter any US-led efforts at regime change.

The Kims have seen the recent history of Iraq and Libya and must surely glean the lesson: give up your nuclear weapons programme and your regime does not survive, wrote Gabrielle Rifkind, director of the Middle East programme, in a piece for The Guardian.

The North says it will never give up its weapons programmes, saying they are necessary to counter hostility from the US and its allies.

It also seeks a formal end to the 1950-53 Korean War which ended in a truce, not a peace treaty.

"They cross line after line in an effort to say this is the new reality and you should accept it and go easy on us," Mount told CNN.

TO GET US TROOPS OUT OF KOREAN PENINSULA

Others point out that Kim's ambitions appear greater than mere survival.

"He is a young man who believes he will be in power for another 40 years. The ICBMs are the key to his long-term strategy...He seems to believe that ICBMs will fundamentally change the balance of power in the region by forcing the United States to withdraw from South Korea. Kim may be right," wrote Thomas Wright on the Lowy Institute website.

Wright cited an interview that Steve Bannon, Trump's former chief strategist, gave to The American Prospect two days before he left the White House.

Bannon said there was no military solution to the ICBM threat and he favoured a deal in which the United States withdrew its forces (currently 28,500 troops) from South Korea in exchange for North Korea freezing its nuclear programme and agreeing to inspections.

Wright adds that, "If the deal came to pass, it would have a devastating impact on North East Asia. It would raise the risk of a new Korean War. Japan and South Korea would go nuclear."

TO SHOW THAT NORTH KOREA CAN STAND UP TO SUPERPOWERS

Mr Rupert Wingfield-Hayes said the latest missile launch is to demonstrate resolve, reported BBC News.

It shows the regime in Pyongyang is not intimidated by American threats and has not "backed down", as President Donald Trump suggested two weeks ago.

Just last week, at a political rally in Arizona, Trump suggested that his threat to rain down "fire and fury" on North Korea if it endangered the United States was beginning to bear fruit. Kim Jong Un, the North Korean leader, was "starting to respect us," Trump said.

In a piece carried in North Korea's official Rodong Sinmun after Tuesday's (Aug 29) launch, Pyongyang said: "The US should know that it can neither browbeat the DPRK with any economic sanctions and military threats and blackmail nor make the DPRK flinch from the road chosen by itself."

DPRK refers to the initials of the North's official name, the Democratic People's Republic of Korea.

TO ADVANCE ITS MISSILE PROGRAMME

With each test, North Korea missile scientists gain valuable insights and data to advance its missile programme. Some experts and US officials have warned that an operational intercontinental ballistic missile (ICBM) capable of reaching the US can be ready by 2018.

This will alter the geopolitical calculus in the region. In fact, Seoul and Tokyo are already looking at more powerful weapons to counter the North following its two tests of ICBM Hwasong-14 last month (July).

North Korea watcher Ankit Panda wrote on The Diplomat website that North Korea has compelling technical reasons to carry out a full-range flight test of its longer-range missiles, including the Hwasong-12 IRBM and even the Hwasong-14 intercontinental-range ballistic missile.

"Flying missiles on trajectories closer to their minimum energy trajectory would help simulate a more realistic stress and temperature endurance profile for the reentry vehicle. "

Its two ICBM launches in July were carried out on lofted trajectories and it needs to test its new missile on a more realistic trajectory in order to give North Korea "important diagnostic information to eventually improve its airframe designs".

He wrote in a piece after North Korea threatened earlier this month (August) to fire missiles into the waters around Guam that "North Korea is likely setting itself up to carry out full-range flight tests of its new IRBM (intermediate-range ballistic missile) and ICBMs.

"It will seek to test them at operational useful trajectories for long-range strikes and, in the process, likely seek to prove its reentry vehicles and gather data on the long-range accuracy of these systems.

Tuesday's missile was fired at what missile experts term "a normal angle" - on the standard trajectory of 30-45 degrees. Experts believe that it is a Hwasong-12 IRBM.

Tuesday's launch also gave North Korea a chance to push the boundaries, Michael Elleman, a missile expert at the International Institute for Strategic Studies, told Washington Post.

"In a way, it's kind of a trial balloon. If we overfly Japan, what happens? If the blowback isn't too significant, they will feel more comfortable with launching a Hwasong-14 to a good distance to validate its performance on a normal trajectory," said Elleman.

DRIVE A WEDGE BETWEEN US AND ITS ALLIES

North Korea's missile tests are aimed at putting a strain on the US-Japan and US-South Korea relationships. They make Japan and South Korea feel extremely vulnerable and tests US resolve. Trump has to assure Abe in a phone call on Tuesday that the US was "100 per cent with Japan", a message he has repeated many times in the past few months.

South Korean and Japanese security specialists have highlighted a more serious danger than a possible North Korean nuclear first strike.

In maintaining their security, South Korea and Japan have depended on the credible commitment of the United States to use all available means to defend them from attack by North Korea, including retaliation with nuclear weapons if necessary, wrote Richard C Bush from the Brookings Institution on the East Asia Forum website.

Among other things, Japan and South Korea have chosen not to acquire nuclear weapons themselves because they believe in the US nuclear umbrella.

"As North Korea's nuclear program inches closer to success, scepticism is increasing in Seoul and Tokyo about the credibility of the US commitment....Would Washington be willing to risk San Francisco in order to save Seoul or Tokyo?" he wrote.