Since the end of World War Two, the world has been built on an idea called deterrence.
It says if you attack me or my allies, I'll retaliate, so we're both better off not fighting.
It's why the Cold War stayed cold, and why there hasn't been a war between major powers
in 70 years.
It's kept the world stable.
It's the reason we still have nuclear weapons — and the reason we haven't used them since
1945.
But deterrence is changing.
New forms of warfare are blurring the old lines and rewriting the old rules.So I went
to ask Secretary of Defense Ash Carter what this means for the world and for the US.
He said the stakes are high, and that the military's challenge will be to establish
new norms of deterrence to convince America's adversaries that the old rules still hold.
It has the word "terror" inside it, right?
"Deterrence."
That's what it's about, is you scare someone away from doing something you don't want them
to do by making them fear the consequences.
To do that, they must know what the consequences are, and you're right, it needs to be understood.
There needs to be some sort of normality to the idea that this threat will be offered
and it should deter.
As we get into new domains, like cyber and space, and we try to situate old and very
solid ideas like deterrence in those new domains, it requires some thought.
The old rules of deterrence set hard, clear lines for what would trigger a military retaliation,
and those lines usually fall across b orders.
But no one knows how or where to draw that sort of line when it comes to things like
cyber attacks.
In the physical world, it's easy to tell when you're under attack by a foreign military,
but not so online.
In 2013, for example, hackers based in Iran accessed the control system for a small dam
in New York state, but it took months for US investigators to accuse the Iranian government
of being behind it.
The hackers didn't cause any physical damage, but they could have, and it raised questions
— which are still unanswered — about when a hack becomes like a military attack, and
when and how the US is obligated to respond.
If you attack us in cyber space, it's an attack.
I'm very straightforward.
An attack is an attack.
We won't necessarily respond in space, or respond in cyber, we may respond in some other
way, but we will respond and you need to understand that: that if you're attacking American interests,
there will be a response.
But it's important to communicate that fact, that you're prepared for it, we know exactly
what we're going to do, and you will regret the consequences of your act and you should
be fearful of those consequences and thus not do it in the first place.
The threat isn't just that new tools of warfare like cyber attacks let countries get away
with things they normally couldn't.
In regular war, we have what are called norms of proportionality.
You bomb me, I bomb you back.
But tools like cyber are so new, there are no norms yet.
No one knows what sort of response to expect, and Carter says this can be dangerous.
Proportionality does mean if you do something, I'm going to do something back to you, but
I'm not necessarily going to do something that's out of proportion and that makes it
necessary for you then to do more, and more, and more.
That's called escalation, obviously nobody wants that.
The US, he says, has to have responses strong enough to make any adversary stand down — but
not so strong that it could make the other country feel obligated to respond, which is
how things could spiral out of control.
So whenever we think about deterrence responses, we craft them in such a way that they are
not by themselves intentionally or unintentionally escalatory.
We always have retained the capability to escalate still further, that's part of deterring
the next move.
But it's not our intention, in general, to escalate something.
It's to stop it from ever occurring in the first place, and if it does occur, to punish
it quickly, which makes the opponent say, "Okay, I realize my mistake.
I stand down from my objectives," and then it's the end of it.
But it's not just cyber war.
Russia is developing new postmodern techniques known as hybrid war.
Special forces dressed up as vigilantes.
Attacks meant to create chaos more than seize territory.
Propaganda and misinformation meant to spark panic or even popular unrest.
Deterrence works on certainty — who is doing what, and what actions will spark retaliation.
But hybrid war is about creating uncertainty.
It makes it harder to determine who's doing what, and blurs the lines between what is
and isn't war.
And, like with cyber war, the rules of hybrid war are still unclear.
Carter says the way to deal with that is by keeping lines of communication open so that
both side can control any misunderstanding or escalation before it gets out of control.
It's very important to keep dialogue, even with potential enemies.
That's why I believe, among many other things, very strongly in military-to-military dialogue
and dialogue between me and my counterparts.
You can't stop a conflict that your enemy deliberately provokes, but you can try to
prevent ones that they blunder into by underestimating you.
One of the ways you do that is by signaling clearly and having dialogue.
Are you satisfied with the level of military-to-military communication with Russia and China?
No, I'd like to see more in general, but it takes two to tango.
It's not just the amount, it's the character of the dialogue and the willingness of those
parties to have a dialogue of a kind that we would regard as fruitful.
That's not everything that it should be.
In the last year of the Obama administration, Carter has been arguing that the American
military needs to prepare for a new era of great power competition, primarily with Russia
and with China.
That means an era where deterrence is even more important.
And that deterrence, ultimately, is backed up by nuclear weapons.
My bedrock of this department here is our commitment to nuclear security, and also to
deterrence in our nuclear arsenal.
It's not in the headlines every day, and thank goodness for that, but it's in the back of
my mind every day.
The US has about 7,100 nuclear weapons, of which about 1,500 are deployed.
Russia has about the same.
Combined, that's 90% of all nuclear weapons.
They mainly exist to never to be used — to deter other nuclear states.
But there's a strange logic to this: to make sure we never have to use them, we need to
credibly threaten to use weapons that would kill millions and send the world into nuclear
winter.
To ask you about that deterrence, there's a story that I love from when Dick Cheney
had your job.
In 1989, he was getting a briefing on US nuclear war plans, and there was a slide that came
up for retaliatory strike plans for Moscow.
One of the things it showed was, I think it was something like 70 strikes on one radar
facility in some suburb of Moscow.
He turned to his aides and he said, "What the hell is this?
Why are we doing this kind of thing?"
The reason I bring that up is I think that's the reaction a lot of people have when they
are confronted with the logic of nuclear deterrence, and they see its ends.
What do you tell people when they have that reaction?
I do, I hear it all the time.
You never get quite used to how terrible such a situation would be.
But until someone has an alternative to deterrence as dealing with someone who might use nuclear
weapons against you — and we haven't found, in all those years since the Manhattan Project,
any effective defense against nuclear weapons — until those are found, the only defense
we have is the threat of retaliation.
As the lines of deterrence blur, what does that mean for nuclear weapons?
The US plans to spend $1 trillion on modernizing its nuclear weapons, and Russia is making
upgrades as well.
Carter says this is about maintaining the status quo, a balance between the nuclear
powers that keeps them away from conflict.
But he acknowledges that this carries some risk.
Do you ever want to use it?
Of course not.
That's the whole purpose, is never to use it.
Thank goodness in all these decades since 1945, a nuclear weapon has not been used in
anger since then.
That's a remarkable achievement.
But it's one I don't take for granted.
But with the growing uncertainty about what does and doesn't triggers retaliation, and
about what kind of retaliation to expect, I asked Carter whether he worried that an
unintended escalation to war could happen.
He said the answer was for the US military to replace that uncertainty with as much certainty
as it could bring.
We have awesome power in our military.
We're not eager to use it, and we hope it causes others not to do provocative things,
but if they do, I don't have any doubt that we will prevail.
We certainly think through every scenario that is possible and make sure that we have
plans that provide for the most sensible thing we could do at the time with the capabilities
we have.
That's what we're here for.
That's a world where stability and peace come from making everyone certain about exactly
when and how the US will use military force.
But there's no such thing as perfect certainty, especially when the technology and norms of
war are changing so quickly.
America's challenge will be to constantly create new norms, and clarify new lines of
deterrence, to keep pace with those changes.
It's a different role than we're used to, but one that we'll need to learn quickly.