Six sets of United Nations sanctions since Pyongyang's first nuclear test in 2006 have failed to halt its drive to create what it insists are defensive weapons.
The sanctions are aimed at severing the economic lifeline of the reclusive North Korean regime, via methods such as limiting coal exports - a vital income channel for Pyongyang - and imposing sanctions on shipping to prevent the trafficking of banned goods.
Major ally and top trading partner China also tightened the screws on Pyongyang last month by banning coal imports from the North for the rest of this year.
But in the wake of North Korea yesterday firing four ballistic missiles towards Japan, with three falling into the waters of its exclusive economic zone, security expert Ken Jimbo of Keio University in Tokyo told The Straits Times that the sanctions "have had little effect on (the North's) determination".
He said the US needs to exercise "extended deterrence and enhanced missile defence as a central role" in its response to the North, so as to show the futility of its nuclear ambitions.
Japan and South Korea are both US allies and house US troops, and both countries have also looked to Washington for defence reassurances.
But this raises the geopolitical risks of an arms race in a region already on tenterhooks, with China and Russia watching defence moves taken by the US-Japan-South Korea triangle with increasing unease.
The missile tests yesterday came three weeks after Pyongyang fired a new type of rocket it claims can carry a nuclear warhead, and amid heightened tensions over the murder of North Korean leader Kim Jong Un's half-brother, Mr Kim Jong Nam, in Kuala Lumpur.
To guard against North Korea, Seoul intends to deploy later this year the United States Terminal High Altitude Area Defence (Thaad) missile defence system, which Tokyo is also apparently keen to procure. China is strongly opposed to the system being deployed on its doorstep, saying it will undermine its security.
There has also been talk within defence circles that the US wants to reintroduce tactical nuclear weapons in South Korea - 26 years after their removal.
Dr Narushige Michishita, the director of the Security and International Studies Programme at the National Graduate Institute for Policy Studies in Tokyo, said that the "strengthening of (US) air- or sea-based tactical nuclear weapons would make much more sense".
Any deployment of nuclear weapons by the US, Dr Jimbo said, would raise its dominance over North Korea, but could backfire by "lowering the threshold" of last resort for the use of nuclear weapons during a crisis.
Dr Bong Young Shik of Yonsei University's Institute for North Korean Studies said that the odds for the worst-case scenario of a surgical strike or a decapitation operation to eliminate North Korea's top brass are low, as it is an "extremely difficult political decision" that would also result in massive retaliation from Pyongyang.
Given the "idiosyncracies" of the leadership in the US and North Korea - which he referred to as "two gorillas thumping their chests but with no real fist fight"- he said that China is best placed to play an intermediary between the two countries.
• Additional reporting by Chang May Choon in Seoul