Unlike many of the other problems Donald Trump is facing, the North Korea issue is not of his own making. This ticking time bomb has been passed from Bill Clinton to George W Bush, to Barack Obama, and on to the current president.

And now Trump is facing an adversary which has a well-running nuclear programme and is probably in possession of chemical and biological weapons of mass destruction. The only certainty around North Korea's nuclear weapons is that they are accelerating in both yield and delivery systems. In addition, North Korea has an army of a million soldiers, dozens of submarines, hundreds of jets, thousands of tanks and tens of thousands of artillery pieces.

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If a conventional conflict without weapons of mass destruction breaks out, the death toll could be anywhere between 30,000 and one million. The last conventional war with North Korea (1950-1953) left over five million dead after three years of bloodshed. And there was no victor.

If war breaks out today, it will progress much quicker than the last one. As North Korea is in the close proximity of several major population centres, the fear of overwhelming losses will demand a military response within less than 20 minutes.

If weapons of mass destruction are used in the chaos that follows, the death toll would grow exponentially. Anything above a couple of dozen nuclear weapons could turn a regional conflict into a nuclear winter, which would have extremely dire consequences for the planet. If China, which is linked to North Korea via a treaty of mutual aid and cooperation joins the conflict, the World War III may break out. Such a scenario can even lead to the extinction of our species.

Mr Trump has three options on how to approach resolving the North Korea crisis.

Amplifying military preparedness

In conjunction with his allies, and especially the president of South Korea, Moon Jae-in, Mr Trump may wish to amplify the military preparedness of the forces facing North Korea. More drills, exercises and deployments of soldiers, vessels and aircraft.

Mr Trump and his allies could also choose to expand the THAAD system of missile air defence. Although the THAAD can be overwhelmed, tricked with decoys or outflanked by submarine launches, it offers, in theory, a type of defence against some missiles (but not the intercontinental ones).

The risk with this approach is that it will lead to both North Korea and China rattling their sabres even louder. Although the chance of these planned events leading to intentional war is very small, the risks of unplanned events caused by paranoia, accidents, mistakes or uncontrolled anger make this one of the most dangerous situations facing humanity since we almost had a nuclear war over Cuba in 1962.

It is impossible to obtain the comprehensive sanctions desired because some countries, especially China, do not wish to squeeze that hard on either the economic or diplomatic veins of their ally.

Tightening sanctions

The second option Mr Trump has is to tighten the sanctions in the hope they will bring North Korea to the negotiating table as they have done with other countries which acted in defiance of the international community.

The United Nations has been squeezing North Korea with sanctions since 2006. These have expanded from a ban on military supplies and luxury goods imports to shutting North Korea out of the global financial system and banning precious metal, coal and iron exports with only a few small exemptions. With the latest round of sanctions, a third of North Korea's exports will be affected.

Mr Trump wants to make the sanctions even stronger by putting oil on the list, making the ban on coal total, banning their national airline, stopping their commodity exports and moving towards a total economic and diplomatic quarantine of the country. This is not a good option for two reasons.

First, it is impossible to obtain the comprehensive sanctions desired because some countries, especially China (which accounts for about 85 percent of North Korea's trade) do not wish to squeeze that hard on either the economic or diplomatic veins of their ally.

Second, even if China did agree to apply the highest level of sanctions possible and the country is made to feel extreme pain, Kim Jong-un does not care. This is the country that the 2014 Commission empowered by the UN Human Rights Council accused of crimes of extermination, murder, enslavement, torture, imprisonment, rape, forced abortions, persecution on political, racial and gender grounds, enforced disappearance of persons and prolonged starvation.

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Weathering pain such as famine to achieve longer-term political goals is something North Korea is fine with. Unlike in Iran, where the pain of the sanctions upon their citizens made those in power listen and then negotiate, in North Korea, the hereditary power and Stalinist-like regime make rulers deaf and insensitive to the impact of sanctions.

A call to Pyongyang

The third option that Mr Trump has is to pick up the phone and talk to Kim Jong-un. The talk could be about concluding a peace treaty for the last Korean war which ended with a truce in 1953. A peace treaty could be supplemented with a number of confidence-building measures, such as the scaling-back of military exercises, removing the missile shield and taking steps towards ending North Korea's isolation.

Promises of non-intervention into North Korea would carry some weight, but not much. Kim Jong-un's fear is that if he gave up his weapons of mass destruction, he would risk suffering the same fate as the other dictators in Iraq, Libya and Syria. Kim Jong-un also knows if he gave up his weapons, his country would be as secure as the Ukraine was next to Russia after they handed over their nuclear weapons on the promise that their sovereignty would be respected.

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This means that Mr Trump would have to accept North Korea having nuclear weapons, at least in the short term. This acceptance would be the same as America and the international community learning to live with both India (in 1974) and Pakistan (in 1998) breaking out of their promises not to obtain nuclear arsenals.

If North Korea can keep their bomb, South Korea, and maybe Japan, will probably seek the same rights. This last option would destroy global efforts of nuclear non-proliferation and it would also chronically upset the balance of power in that part of the world.

In that sense, Mr Trump has no good options on resolving the North Korea crisis.

Alexander Gillespie is professor of international law at the University of Waikato, New Zealand. His research focuses on laws of war and armed conflict. He is the author of the three-volume set "A History of the Laws of War" and the three-volume set "The Causes of War".

The views expressed in this article are the author's own and do not necessarily reflect Al Jazeera's editorial policy.