(Bloomberg Opinion) -- I spend a great deal of my life thinking about nuclear weapons. You can imagine I'm murder at a cocktail party. As the Cold War faded, and the possibility of a nuclear holocaust with it, people like me were considered yesterday’s news. Now, as the world enters a renewed era of great-power competition, I like to think we were simply prescient.

If so, there was a whole lot of prescience on display at the Council on Foreign Relations last month at an event aptly titled “Do Nuclear Weapons Matter?” It featured a lively and intelligent debate between Nina Tannenwald of Brown University and Elbridge Colby, director of the defense program at the Center for a New American Security. She took the “no” side and he took the “yes.” While I like to maintain a journalistic objectivity, there may be a clue to my bias in that I decided to interview him.

Before Colby signed on at CNAS, he was the deputy assistant secretary of defense for strategy and force development in the Trump administration. That convoluted title came with a convoluted task: leading the policy process for the first U.S. National Defense Strategy in a decade. Here is a lightly edited transcript of our discussion:  

Tobin Harshaw: The Trump administration has made the decision to pull out of the Intermediate-Range Nuclear Forces treaty with Russia, which banned land-based missiles with ranges between 300 and 3,400 miles. Do you think that that was the right move?

Elbridge Colby: Yes. But my reason is bit different than what you often hear, which is Russian noncompliance. That’s an issue -- but in and of itself, I'm not sure it would justify a withdrawal. I'm of the view that arms control exists fundamentally to serve our security and defense interests; it’s a tool, not an end of its own. And the reality is, we don't really need INF-class systems for effective European deterrence and defense.

The real causal factor that makes me think it's the right idea is China. The INF covers both nuclear and conventional systems globally. This limits the U.S. in Asia, where we face the continuing trajectory of the growth of Chinese military power. Some people say this isn’t a problem; we have air- and sea-launched intermediate-range systems. That’s true, but the problem is those systems are much more expensive than land-based missiles. And the nature of the geography in the Pacific makes our footprint very concentrated, so it's very vulnerable to the large Chinese missile inventory, which is much, much larger than the Russian inventory.

TH: Let’s talk about the Russian response. Is there a way to renegotiate?

EC: If the Russians gave us confidence that they would honor it, we could. I doubt they would go for a ban on nuclear-class intermediate-range weapons, but it could have ceilings, and we'd have transparency measures. It would look more like New Start.

TH: Putin has said he would like to keep New Start – which heavily limits intercontinental ballistic missiles -- after its current expiration date in 2021. Could we bring reviving the INF into that?

EC: We definitely need to look at it. Look, when you really want arms control is with people whom you don't trust and you think you might go to war with. But we want to end up with an arms control regime that’s actually adapted to the security situation today. And the reality seems to me that the Russians want INF-class systems.

But the real defense problem we have with the Russians, their theory of victory, is that they have time and distance advantages with respect to Eastern European NATO members. We need to address that through changes in our posture, through exercises that show we can get there faster. The solution is not for us to deploy INF missiles in Europe.

TH: So you think the current U.S.-NATO tripwire force in the Baltics is insufficient?

EC: Yes, we need a better force posture for Eastern NATO. What we want is a force that compels the Russians, if they invade, to have to invade in a way that shows how aggressive and malign their intentions are. I think it's totally possible that if you just have a tripwire force, the Russians could just ignore or go around them. This doesn’t necessarily mean we need a lot of forces in the Baltics, but it means a force that can contest the Russians from the get-go. And this is what the National Defense Strategy is really directing the Department of Defense and asking our allies to do.

Rather than deploying INF-class systems, I'd put more heavy equipment and munitions in Europe. I'd rather conduct more exercises with the Germans and the Poles and so forth to get ready to respond very rapidly to a Russian effort to take the Baltics.

TH: Here’s an easy one: Can you boil down into a few sentences what is the ideal nuclear posture for the new threats we face?  

EC: The ideal nuclear posture is one designed to credibly deter Russian or Chinese escalation options over vulnerable allies of ours in Eastern Europe or the western Pacific. This involves a combination of conventional and ultimately nuclear forces. And in particular it means combat-credible conventional forces that can blunt or deny a Russian or Chinese fait accompli. And then a set of nuclear forces that offer a set of discriminate options that can contribute to that blunting if it gets to that level, and ultimately have the ability to devastate the other side’s society so they know that's never a rational option.

TH: How would so-called tactical nuclear weapons, which can be dialed back to a yield far smaller than the Hiroshima bomb, fit into that?

EC: Low-yield is a must-have. We've had low-yield weapons forever. We've been grappling with the problem of limited nuclear war since the late 1950s, and we've always had those options.

The issue today is the increasing sophistication of Russian and Chinese air defense, which makes it harder to be confident you’re going to have the effect that you want. So the low-yield ballistic missile option on the submarine is great because it's really, really hard to intercept a ballistic missile. And that means I know exactly what the impact is going to be. Whereas if I have to send a couple of tactical aircraft into the teeth of a Russian air defense system, I don't know what's going to happen. So I want the Russians to understand that I have credible options that are suited to dealing with their theory of victory. Now we actually don't need big changes in our nuclear force. It's pretty marginal. What we would really benefit from is the ability to use nuclear weapons in this very specific, precise way.  

TH: That said, there’s a lot of debate about what we call the nuclear triad: air, submarine and the intercontinental missiles in silos. Would you emphasize one leg and de-emphasize the others?

EC: Submarines are the most survivable, and there are a lot of warheads on them. But I think we benefit from all legs, especially considering the cost. Given that we are building them for the next 50 or 60 years, we should be very humble about the future and putting our eggs in one basket. It complicates the other side's planning if they have to deal with multiple threats.

TH: Let’s get off nukes and switch to China. Are we able to do anything about the militarization of the South China Sea?

EC: The South China Sea is a species of a larger challenge, which is basically about the growing threat or challenge of a Chinese bid for regional hegemony. The Chinese are militarizing features in the South China Sea I think to cast a shadow over the regional states and thereby dissuade them from growing closer to us to balance the Chinese. It seems to have had some success, say with the Philippines. I think the Chinese understand that they still don't have the military advantage, but if we don't get our act together the trend is going in that direction.

What's critical in Asia is to make sure that the states of the region -- and not just our traditional allies -- have autonomy and independence and are able to interact with us in an uncoerced way. Our strategic interest is in their autonomy, which presumably they share. We should be encouraging them to improve their own military options like developing anti-access/area-denial systems. They're not going to reach the sophistication of the Americans or the Chinese -- but if the regional countries can make it hard for the Chinese to project power, that's pretty nasty and good for all of us.

What the Chinese are going for is the ability to establish suzerainty over the region that would allow them to create a regional economic system favorable for them and unfavorable to us. So we want to counter that. Ultimately that's a military question because international politics is ultimately decided by military power, but obviously economic power is enormous. Economic power turns into military power.

TH: We've talked mostly great-power competition. Let’s talk regional problems. How big of a threat is Iran?

EC: It is far, far less of a military threat than China in particular or Russia. Iran we can definitely handle militarily. If our basic focus is ensuring that it doesn’t establish hegemony over one of the wealthiest parts of the world, we can always stop Iran from doing that.

So my view is that we need to bring our military commitment in the Middle East way down. It's not about getting out. It’s about how do we work with locals but also use our own forces in a more cost-effective and efficient way.

TH: As we pivot to our great-power threats, are you worried that counterterrorism will go the back burner, with the result that al-Qaeda gets stronger, the Taliban gets stronger and ISIS makes a comeback?

EC: From a military perspective, terrorism hasn't really been our main focus. The most effective way to deal with terrorists is not to put 100,000 troops on the ground and exacerbate people's hostility to the U.S. Rather, it's to have very aggressive and focused intelligence, diplomatic and -- as appropriate -- military capabilities. You don't need to use a B-2 to attack a terrorist safe haven.

A certain part of the military -- Special Forces -- is going to stay really focused on that problem while the majority of the military focuses on great power.

TH: Your NDS had a lot to swallow. Then there was a review of it by a commission – which included Bloomberg View columnist Hal Brands -- and there's a lot to swallow there. But in a nutshell, what do you think are the biggest takeaways? For the public as well as for the military.

EC: I think the main thing is getting back to a real focus on thinking about actually fighting a war against a great power that is a near-peer, that is an opponent that you can't just dominate. For the American public and for our allies what this is saying is: “The countries that can really fundamentally undermine our way of life, even if they don't seem so malign, are the great powers and particularly China.” I mean these are the countries they can impose their will on the world. Terrorists and rogue states can do a lot of damage, but if we resist them enough, as we're more powerful, we will win. With great powers that's not necessarily the case.

TH: So when the report from the commission that reviewed your NDS came out, the press glommed on to the part that said we could potentially lose a war to China or Russia. Did you think that was overstated?

EC: Not at all. I think that's absolutely right. And I thought there was a lot of great stuff in the commission report. Yet what the commission report is basically saying is yes, the NDS is right, there needs to be change, but we can't afford to make the kind of hard choices it is calling for. It says you should grow the Army, grow the Navy, don't cut the Marines and then don't reduce our forward presence in the Middle East -- and give us more money. Realistically, it's very unlikely that there's going to be a major increase in defense spending given the Democrats taking over the House. But moreover, even with that extra money, you still wouldn't be able to do all these things. So we have to make hard choices.

TH: It’s taken as a truism among people in our professions that America’s greatest strength is its network of allies. How do we repair the damage done to those alliances by Trump personally?

EC: Yes, the network of allies is our greatest advantage, but we need a fundamental change that the president is accurately putting his finger on -- which is that we actually can't do this alone. We can't afford it in the face of Chinese military power, not to mention the Russians and all the other things going on. We need to get our allies to do a lot more, but in a way that's sustainable, and not just traditional allies but countries like India and Vietnam.

We've actually had some pretty good indications. The Germans have recommitted to collective defense. They’re on a slow glide path to increase defense spending, which is encouraging. They could do more. Japan I think is coming out with very good national defense planning guidelines. Again, they need to increase their defense spending. Taiwan, which is crucial, has started to move.

TH: So, last question, and it's semantic. Are we in a new Cold War with China?

EC: It's going to have a lot of features of the Cold War, because it's going to move toward rivalry. This notion that we need China to solve problems like climate change and nuclear proliferation is completely misplaced. The way the Chinese, for instance, are going to end up putting more pressure on North Korea is if they think that otherwise the world is going to be worse. If they don't think that, then they won’t. It's going to be a cost-benefit analysis.

The Cold War was different because it was with a completely closed economic system and a political order that was absolutely antithetical from an ideological perspective. There's gonna be a lot more interaction with China. There needs to be. But I do think we're going to move toward more disengagement -- because the rivalry is going to become more intense.

To contact the author of this story: Tobin Harshaw at tharshaw@bloomberg.net

To contact the editor responsible for this story: Philip Gray at philipgray@bloomberg.net

This column does not necessarily reflect the opinion of the editorial board or Bloomberg LP and its owners.

Tobin Harshaw writes editorials on national security and the military for Bloomberg Opinion. He was an editor with the op-ed page of the New York Times and the paper’s letters editor.

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