Does launch on warning assume incoming ICBMs carry nuclear warheads?

Question

The launch on warning doctrine holds that:

a retaliatory strike is launched upon warning of enemy nuclear attack and while its missiles are still in the air, before detonation occurs

Although it is straightforward to tell that ICBMs are coming in, it would seem that telling the payload is much harder, in particular if launched from submarine or subterranean launch sites. Does launch on warning assume any incoming ICBM is carrying nuclear warheads, or is there reliable information on the explosive payload available?

If based on assumption, it would seem that launch on warning carries the risk of misclassifying incoming ICBMs carrying non-nuclear payloads for nuclear ones, and therefore escalating a non-nuclear war into a nuclear one.

Answer 1

It probably is a lot harder to tell what the payload is. Like, radiation and chemical measurements would probably require a short-ranged interaction, so you'd need to get closer—way too close—to the rocket. Maybe if you knew the starting point and the design of the rocket, you could make speculations by looking at the weight distribution and how it affects the trajectory of the rocket, it's range and the fuel type. But, then again, these rockets are supposed to be really fast, and, if launched covertly, this information might come too late to be assessed.

So, yeah, most likely it's just assumed that an ICBM carries a nuclear warhead as it would a) be a waste of resources not to and b) the other side probably confuses it for one anyway. So it's somewhat like pointing a toy gun at a cop and pretending to pull the trigger. Sure, the cop is likely to escalate, but you'd also be a moron to not see that coming.

Answer 2

BTW, in the event that probably motivated this Q, Russia had apparently warned the US that it was about to launch a less-than-usual missile at Ukraine.

Russia warned the US of an incoming ballistic missile strike on Ukraine shortly before Thursday’s attack, a US administration official told Semafor.

“The United States was pre-notified briefly before the launch,” the official said.

The US also briefed Ukraine and other allies in the days leading up to the attack about Russia’s possible use of an experimental medium-range ballistic missile “to help them prepare,” the official said.

Russia and the US typically inform each other if they plan to fire such missiles, however it was unclear whether or not Moscow had done so this time.

Probably because it might have been confounded (upon launch) with an attack on some other country in Europe, at least, had they not issued that warning. (The White House Press Secretary said Russia fired an IRBM. Putin said they fired an 'experimental hypersonic' MRBM.)

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Interestingly enough, I see Russia denies that they sent any such notifications.

MOSCOW, November 21. /TASS/. Russia did not send advance notifications to the United States or other countries about the use of the Oreshnik hypersonic missile on a Ukrainian military-industrial facility as there are no such obligations, Kremlin Spokesman Dmitry Peskov told TASS.

"No, there have been no notifications, for Russia has no such obligation with regard to intermediate-range missiles," the spokesman emphasized.

So, for now take your pick whom to believe.

Strangely enough TASS also carries this:

When using Oreshnik, Russia will issue warnings in advance: "We shall openly and publicly do it for humanitarian reasons without fear of hostile counteraction. Why without fear? Because no means to counter this weapon exist today."

Apparently quoting Putin. So maybe they "will" in the future but they haven't in this case?! Or Peskov didn't get the memo.

Thanks to user111403 for pointing out that Peskov also said the opposite (in Russian):

"The Russian side warned the Americans about the launch of the Oreshnik through the Russian National Center for Nuclear Risk Reduction, which operates in automatic mode and maintains constant communication with a similar system in the United States of America," Peskov told TASS. "The warning was sent in an automatic mode 30 minutes before the launch," he specified.

Also, the US has now said that Russia fired a modified ICBM.

The US military said the Russian missile’s design was based on the design of Russia’s longer-range RS-26 Rubezh intercontinental ballistic missile (ICBM).

The new missile was experimental and Russia likely possessed only a handful of them, officials said.

The Pentagon said the missile was fired with a conventional warhead but that Moscow could modify it if it wanted.

In this context the warning would make more sense as you probably can't tell based on launch if it's an ICBM or has a heavier (conventional) payload and thus shorter rage. BTW, South Korea (which doesn't have their own nukes) also uses an ICBM-like design but with a very heavy conventional "bunker busting" warhead, and thus substantially shorter range.

I also found the DOD statement itself.

"This IRBM was based on Russia's RS-26 Rubezh intercontinental ballistic missile model. In terms of notifications to the United States, the United States was prenotified, briefly, before the launch, through nuclear risk reduction channels."

[The deputy Pentagon press secretary ...] Singh also said an IRBM and an intercontinental ballistic missile have similar flight paths, high trajectories and can carry large payloads.

"But the main difference lies in the range and the strategic purpose," she said.

The prenotification also makes sense given that Putin says Russia has the right to strike countries arming Ukraine.

Answer 3

"...the risk of misclassifying incoming ICBMs..." Also goes the other way around. What if there is indeed a nuclear payload? You don't want to find out when it's too late or your whole defense against ICBMs strategy would be worthless. The important point is that they can carry nuclear payload (and in most cases do), not that they don't have to, resulting in exactly this assumption you mention.

That's why nobody sane would shoot an ICBM with or without nuclear payload without warning or against somebody who also is in possession of ICBMs. That would risk nuclear war and total annihilation.

Even a false alarm or just the mistaken possibility of a launch of an ICBM are already risky. See for example the 1983 Soviet false alarm, when Soviet officers believed the US had launched missiles, but thankfully decided not to act on it.

Somebody acting according to the madmen theory would try to come close to this border in order to simulate irrationality and gain an advantage, but playing the nuclear madman is of course very, very risky for everyone. The madmen might feel not be taken serious enough and ups the ante and accidentally triggers nuclear war in the end.