How did India and Pakistan avoid war when India accidentally launched a missile at Pakistan?

Question

India claims that on March 9, 2022, it accidentally launched a missile at its neighbor and frequent adversary Pakistan. The two countries:

have fought three wars and have engaged in numerous military clashes, most recently in 2019 which saw the air forces of the two engage in combat.

Both nations have nuclear weapons.

Conventional wisdom holds that a country launching a missile at your country, especially, when both countries have nuclear missiles, is the kind of thing that is viewed as an act of war that calls for an immediate response in kind with little time for deliberation.

How did India and Pakistan avoid going to war in this incident?

Answer 1

At present I cannot find any quotes that definitively nail down what the rationale of Pakistani leadership was for this particular event. There are some details and government responses that at least provide a chance to draw inferences, though.

Here's a NY Times article with quotes and information from various ministries and personages on both sides. Evidently India did not communicate with Pakistan about the incident any earlier than it did the rest of the world (two days later). So the muted response is definitely quite surprising.

One major factor to note is that the missile did not hit any military structures, aircraft, or population centers, and tensions between the countries were not at a particularly elevated level at the time. The missile also did not have a nuclear warhead. These would all help to contribute to interpreting the event as not an actual act of war.

Initial news reports in Pakistan thought the damage resulted from a crashed airplane, which likely also damped any initial popular outrage or concern. According to Moeed Yusuf, national security advisor for Pakistan, the missile traveled close to paths of international and commercial airline flights. This certainly elevated the potential risks of the launch, but may have also helped create the initial reports of a plane crash.

This Indian Express article provides further details on exactly how this event unfolded that may help explain Pakistan's level-headed response.

It notes that originally the missile was launched about 104km south of the Pakistan border and initially traveled some 70-80km southwest further into India. It then took a turn and traveled northwest, eventually heading into Pakistan. This is not an expected flight pattern for any such missile, according to Retired Air Marshal Anil Chopra.

It ends with the following:

The Pakistani military said on Thursday that the “high-speed flying object” was picked up inside Indian flying territory by the Air Defence Operations Centre of the Pakistan Air Force. They knew it had taken off from Sirsa, and after its initial course it suddenly manoeuvred towards Pakistani territory and violated Pakistan’s airspace ultimately falling near Mian Channu.

It stated that the Pakistani Air Force initiated requisite tactical actions in accordance with the Standard Operating Procedures, and continuously kept monitoring it and as soon as it turned towards Pakistani territory. But during this time it did not intercept the incoming missile, which was unarmed.

So the Pakistani Air Force was evidently well aware of the launch and moreover its unusual flight path. While one might imagine attempting to "sneak attack" with a deceptive and sudden change in trajectory, it's also possible that the unusual behavior, which would only give Pakistan more time to notice and respond, was taken as indicative of some sort of error or other bizarre circumstance.

Answer 2

Pakistan and India avoided nuclear war because the incident did not reach any of the the threshold levels for Pakistan's nuclear weapons to be used

Spatial threshold - The military penetration of Indian Armed Forces into Pakistan on a large scale may elicit a nuclearized massive retaliation, if and only if the Pakistan Army is unable to stop such intervention. (snip)

Military threshold - The complete knockout or comprehensive destruction of a large part of the Pakistan Armed Forces, particularly and most importantly the Pakistan Air Force (PAF), could lead to a quick nuclear response if Islamabad believed that it was losing the cohesiveness of its defence and feared imminent defeat. (snip)

Economic threshold - This level implicitly and explicitly refers for the countermeasure operations of the Pakistan Navy. Economic strangulation and economic blockade is also a potential threat to Pakistan, if the Navy is unable to counter it effectively (snip)

Political threshold - Finally, Pakistan's geostrategists, game theorists, political strategists and planners suggest that a destabilization of the country by India could also be a nuclear threshold if Islamabad has credible reasons to believe that the integrity of the country were at stake. (snip)

The main point being that conventional wisdom DOES NOT hold that a country launching a missile at your country, especially, when both countries have nuclear missiles, is the kind of thing that is viewed as an act of war that calls for an immediate response. Nuclear weapons have not been used since 1945 because their use is perceived to be so devastating and taboo that

Abstention from the use of any NW [nuclear weapons] is universally recognized as a political and psychological threshold, however rational or irrational the distinction between ‘nuclear’ and ‘nonnuclear’ may be.

Nuclear weapons have been successful as deterents to war. The incident was clearly not the start of a war between India and Pakistan. There was no concerted attack on Pakistan and it seems to have taken a couple of days for both side to realise what had happened.

There have been other similar events; The US bombing of the Chinese embassy in Belgrade, and a whole list of cold war incidents.

Answer 3

If we compare this incident with the last escalation in 2019, we can get the answer.

On 19th February 2019, a few days before India planned to drop a bomb on Pakistani soil, Pakistan's prime minister Imran Khan went to the television and warned India in a televised speech that:

If you think that, you will launch any kind of attack on Pakistan, then Pakistan won't just think about a retaliation; but Pakistan will definitely retaliate.

That was proof that Pakistan had an intelligence report well before India was preparing for an attack on Pakistani soil.

Then on 26th February 2019, when India dropped a bomb in the middle of a jungle inside Pakistan, Pakistani military and civilian leadership held a closed-door discussion and planned how they would execute a retaliation.

Therefore, we can see a pattern here, and let us check what happened in the case of the latest missile fire on March 9, 2022.

Firstly, Pakistani intelligence didn't have any information that India was preparing to launch a supersonic missile with an intention to attack. So, they were not panicked.

Secondly, the missile landed without any civilian or military casualties. So, again, Pakistan felt no need for escalation.

Thirdly, the missile was unarmed i.e. there was no warhead. Again, no need for retaliation.

Now, the question is: what if an Indian missile had a warhead?

Again the answer depends on intelligence. If India planned a bona fide attack, Pakistan would have known that well in advance. However, since Pakistan doesn't have the capability to intercept a supersonic cruise missile (in fact, neither does India), Pakistan would have waited, civil-military leadership would have had a consultation, and then they planned an appropriate retaliation.

This would have been the same if India launched a nuclear strike.