WASHINGTON (WASHINGTON POST) - North Korea, if not stopped, will build an arsenal with multiple nuclear missiles meant to threaten the US homeland and blackmail us into abandoning our allies in Asia.
North Korean dictator Kim Jong Un will sell these weapons to state and nonstate actors, and he will inspire other rogue actors who want to undermine the US-backed post-war order.
These are real and unprecedented threats. But the answer is not, as some Trump administration officials have suggested, a preventive military strike.
Instead, there is a forceful military option available that can address the threat without escalating into a war that would likely kill tens, if not hundreds, of thousands of Americans.
When I was under consideration for a position in this administration, I shared some of these views.
Some may argue that US casualties and even a wider war on the Korean Peninsula are risks worth taking, given what is at stake.
But a strike (even a large one) would only delay North Korea's missile-building and nuclear programmes, which are buried in deep, unknown places impenetrable to bunker-busting bombs. A strike also would not stem the threat of proliferation but rather exacerbate it, turning what might be a North Korean moneymaking endeavor into a vengeful effort intended to equip other bad actors against us.
I empathise with the hope, espoused by some Trump officials, that a military strike would shock Pyongyang into appreciating US strength, after years of inaction, and force the regime to the denuclearization negotiating table.
I also hope that if North Korea did retaliate militarily, the United States could control the escalation ladder to minimise collateral damage and prevent a collapse of financial markets. In either event, the rationale is that a strike that demonstrates US resolve to pursue "all options" is necessary to give the mercurial Kim a "bloody nose".
Otherwise he will remain undeterred in his nuclear ambitions.
Yet, there is a point at which hope must give in to logic. If we believe that Kim is undeterrable without such a strike, how can we also believe that a strike will deter him from responding in kind? And if Kim is unpredictable, impulsive and bordering on irrational, how can we control the escalation ladder, which is premised on an adversary's rational understanding of signals and deterrence?
Some have argued the risks are still worth taking because it's better that people die "over there" than "over here".
On any given day, there are 230,000 Americans in South Korea and 90,000 or so in Japan.
Given that an evacuation of so many citizens would be virtually impossible under a rain of North Korean artillery and missiles (potentially laced with biochemical weapons), these Americans would most likely have to hunker down until the war was over.
While our population in Japan might be protected by US missile defences, the US population in South Korea, let alone millions of South Koreans, has no similar active defences against a barrage of North Korean artillery (aside from counterfire artillery).
To be clear: The president would be putting at risk an American population the size of a medium-size US city - Pittsburgh, say, or Cincinnati - on the assumption that a crazy and undeterrable dictator will be rationally cowed by a demonstration of US kinetic power.
An alternative coercive strategy involves enhanced and sustained US, regional and global pressure on Pyongyang to denuclearise.
This strategy is likely to deliver the same potential benefits as a limited strike, along with other advantages, without the self-destructive costs. There are four elements to this coercive strategy.
First, the Trump administration must continue to strengthen the coalition of UN member states it has mustered in its thus far highly successful sanctions campaign.
Second, the United States must significantly up-gun its alliances with Japan and South Korea with integrated missile defence, intelligence-sharing and anti-submarine warfare and strike capabilities to convey to North Korea that an attack on one is an attack on all.
Third, the United States must build a maritime coalition around North Korea involving rings of South Korean, Japanese and broader US assets to intercept any nuclear missiles or technologies leaving the country. China and Russia should be prepared to face the consequences if they allow North Korean proliferation across their borders.
Lastly, the United States must continue to prepare military options. Force will be necessary to deal with North Korea if it attacks first, but not through a preventive strike that could start a nuclear war.
In the land of lousy options, no strategy is perfect, but some are better than others. This strategy gets us out of crisis-management mode. It constitutes decisive action, not previously attempted, by President Donald Trump. And it demonstrates resolve to other bad actors that threats to the United States will be countered.
Such a strategy would assuredly deplete Pyongyang's hard currency, deter it from rash action, strengthen our alliances in Asia for the next generation and increase the costs to those who continue to subsidise Pyongyang.
A sustained and long-term competitive strategy such as this plays to US strengths, exploits our adversary's weaknesses and does not risk hundreds of thousands of American lives.
The writer is a professor at Georgetown University and senior adviser at the Center for Strategic and International Studies. This commentary was carried by the Washington Post following reports that Prof Cha was no longer being considered for the post of the next US ambassador to South Korea.
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