India and Pakistan have significantly upgraded their military capabilities since the South Asian neighbours faced off in a military confrontation in 2019.
Both sides have acquired more sophisticated aircraft, missiles and drones.
And they have stockpiles of nuclear warheads, but defence experts stress it is unlikely either side will consider using them.
But with both boasting powerful conventional weapons, even a limited conflict would carry high risks of escalation.
Balance in power, not numbers
India has been building up its military might, largely due to increased Western support.
Pakistan gets 81 per cent of its weapons from China, according to the Stockholm International Peace Research Institute.
The two countries are roughly balanced in terms of their military capabilities, but they differ substantially in numbers.
India has the world's second-largest military behind China, according to World Factbook data.
The Stockholm International Peace Research Institute reported that India's military expenditure in 2024 was $US86.1 billion ($133.7 billion), making it the fifth-largest military spender globally.
India's far greater resources would come into play over a longer period.
Tensions boil over
Indian and Pakistan have fought three wars — in 1948, 1965 and 1971 — and clashed countless times, mostly over the Kashmir region which they both claim.
Kashmir is considered one of the most dangerous flashpoints in the world.
Pakistan's leader vowed his country would deliver a robust response after India launched missiles into Pakistani territory on Wednesday.
India said it was targeting "terrorist infrastructure" in Pakistan after 26 tourists were gunned down in India-controlled Kashmir.
The countries have since accused each other of launching missile and drone strikes.
A ceasefire agreement was reached on Saturday, but both sides have already accused each other of violations.
The 2019 skirmish almost spiralled out of control, with multiple missile strikes threatened before US intervention calmed the situation down.
Muhammad Faisal, a South Asia security researcher based at the University of Technology Sydney, said a prolonged conflict today would likely involve more advanced weapons.
"Each side will think they are in a better position than last time," he said.
"It is only when we see actual combat that we will find out."
India's Western air power
According to data from the London-based International Institute for Strategic Studies, India has about 730 combat-capable aircraft.
India believed it was at a disadvantage in 2019 because it had to rely mainly on aging Russian jets.
It has since acquired 36 French-made Rafale fighter jets, a top Western aircraft, with more on order for its navy.
"For India, there is the dilemma of how many air squadrons to commit to the Pakistan front, as it must also guard against China," Mr Faisal told the ABC.
The Pakistani prime minister's office said on Wednesday that five Indian fighter jets and drones had been shot down by Chinese-made J-10C jets, although this was not confirmed by India.
An anonymous US official told Reuters at least one Indian jet that was shot down was a French-made Rafale fighter aircraft.
The Indian embassy in Beijing called reports of fighter jets downed by Pakistan "disinformation".
Pakistan could test China jets
Pakistan's aerial fleet is much smaller, at about 450 aircraft.
Since 2022, Pakistan has acquired at least 20 Chinese-made J-10C jets, one of the country's most advanced fighter aircraft.
India's Rafales are armed with Meteor air-to-air missiles.
The Meteor's range has not been officially published.
The J-10 is equipped with the comparable PL-15 missile, a Pakistani security official told Reuters.
The Chinese plane and its PL-15 missiles have never been tested in combat.
The PL-15 missile is reported to have an estimated range of 200 km.
Mr Faisal said fighter jets would likely continue to feature in any prolonged stand-off.
They allow each side to strike at long-range targets from their own territory.
"Jets allow you to send missiles simultaneously across the border and overwhelm air defences," he said.
"It could be a contest between Western and Chinese technology."
To plug the gaps in air defences exposed on both sides in the 2019 conflict, India secured Russia's battle-tested S-400, a mobile anti-aircraft missile system.
Pakistan obtained the HQ-9 from China, which is based on Russia's S-300, one notch down.
India's S-400 could also be integrated into its navy.
Mr Faisal said India had ambitions beyond defending itself against Pakistan.
He said it also had to consider risks from China, and was investing in its naval forces to have a footprint across the Indo-Pacific.
'High-intensity' ground fighting
Border skirmishes between the two countries are common.
There have been reports of Indian and Pakistani troops engaging in post-to-post small arms firing along the Line of Control (LoC) in Jammu and Kashmir since last month's deadly terrorist attack in the area.
Sushant Singh, a lecturer at Yale University and a former Indian army officer, said fighting along the Line of Control last week had reached new levels.
He said there was "very high intensity of firing" using "a very different kind of weaponry … bigger weaponry, more powerful weaponry is being used by both sides," he told the ABC's Radio National Hour.
Missiles and drones increasingly important
Both India and Pakistan have been heavily investing in drones.
India has turned to Israel for combat-capable drones, receiving Heron MK2s — long-endurance drones used for strategic missions.
It also has US Predator drones on order.
According to the Stimson Center, a US-based think tank, one of the most notable developments in India's drone program has been the deployment of swarm drones.
Pakistan's drone fleet includes Turkey's advanced Bayraktar TB2 — used by Ukraine in its war with Russia — and the Akinci, according to the Pakistani security official.
It also has long-endurance, Chinese-made Wing Loong I and II drones.
Pakistan said it shot down 12 drones from India that violated its airspace on Thursday.
India sent Israeli Harop drones to multiple locations, including the two largest cities of Karachi and Lahore, Pakistan military spokesperson Ahmed Sharif Chaudhry said.
India's defence ministry did not immediately respond to a request for comment.
India also claimed to have neutralised Pakistani missile and drone strikes on military stations around the Kashmir region.
Mr Faisal said both countries had ballistic missiles that could cover each other's "whole territory".
"They both have developed missiles that are aimed at each other's nuclear facilities and command and control centres in case of war," he said.
Pakistan tested a surface-to-surface ballistic missile with a range of 450km last Saturday.
The country's military said it was to show its forces were ready to "safeguard national security against any aggression".
Nuclear war highly unlikely
Marcus Hellyer from Strategic Analysis Australia said any full-scale conflict or use of nuclear weapons would be highly unlikely.
"While it's not complete parity, you don't have this huge imbalance of power, so that kind of limits the options," he told the ABC.
"So there's really not a way to resolve the underlying issue of Jammu and Kashmir by force."
The countries have built up nuclear arsenals over the years.
India has 172 warheads and Pakistan boasts 170, according to data from the London-based International Institute for Strategic Studies.
They are both signatories to a pact that bars them from attacking each other's nuclear facilities.
India also has a "no first use" policy. That means it will only retaliate with nuclear weapons if there is a nuclear attack on Indian forces or Indian territories.
Raji Pillai Rajagopalan from the Australian Strategic Policy Institute said the Indian and Pakistani political leadership had limits.
They "cannot escalate it to a nuclear level", she told ABC News Breakfast.
"Even after the two countries went nuclear in 1998, they have engaged in multiple conflicts but have always been limited in nature," she said.
"Every single attack has shown that there are these kind of red lines that both sides draw."
ABC/wires
