India has carried out air raids on rebel camps inside Pakistan weeks after a suicide attack in the disputed Kashmir region, raising fears of a war between the nuclear-armed South Asian nations.
At least 42 Indian paramilitary personnel were killed in the attack claimed by Pakistan-based rebel group, Jaish-e-Mohammad (JeM).
Indian Prime Minister Narendra Modi vowed a strong response in the wake of the worst attack on soldiers in decades.
Pakistan downplayed Tuesday's incident, saying Indian aircraft violated Pakistani airspace and that Indian jets "released a payload" hastily in a forest area after crossing the Line of Control, the de facto border that divides Indian- and Pakistan-administered Kashmir.
Here is how their militaries stack up.
In 2018, India allocated four trillion rupees ($58bn), or 2.1 percent of its gross domestic product (GDP), to support its 1.4 million active troops, according to the International Institute for Strategic Studies (IISS).
Last year, Pakistan spent 1.26 trillion Pakistani rupees ($11bn), about 3.6 percent of its GDP, on its 653,800 troops. It also received $100m in foreign military assistance in 2018.
Between 1993 and 2006, more than 20 percent of Pakistan's annual government expenditure was spent on the military, according to estimates from the Stockholm International Peace Research Institute (SIPRI).
The military accounted for 16.7 percent of government spending in 2017, it said.
By comparison, India's military spending as a percentage of its government expenditure remained under 12 percent during the same period, according to SIPRI. It was 9.1 percent in 2017.
Missiles and nuclear weapons
Both nations have ballistic missiles capable of delivering nuclear weapons.
India has nine types of operational missiles, including the Agni-3 with a range of 3,000km to 5,000km, according to the Center for Strategic and International Studies (CSIS) in Washington.
Pakistan's missile programme, built with Chinese assistance, includes mobile short- and medium-range weapons that can reach any part of India, CSIS said. The Shaheen 2 has the longest range, up to 2,000km.
In 2011, Pakistan confirmed that it had acquired tactical nuclear weapon capability, wherein smaller nuclear warheads are attached to short-range missiles (50-100km) as a deterrent against relatively small-scale conventional Indian attacks.
The addition of tactical nuclear weapons to Pakistan's arsenal lowers the threshold for nuclear weapon use, giving Pakistan what its military terms "full spectrum deterrence" against India's conventional forces.
The weapons were developed to counter India's "Cold Start" doctrine, which envisions a shallow incursion into Pakistani territory without breaching its previous nuclear threshold.
Pakistan has 140 to 150 nuclear warheads, compared with India's 130-140 warheads, according to SIPRI.
India has a 1.2 million-strong army, supported by more than 3,565 battle tanks, 3,100 infantry fighting vehicles, 336 armoured personnel carriers and 9,719 pieces of artillery, according to IISS.
Pakistan's army is smaller, with 560,000 troops backed by 2,496 tanks, 1,605 armoured personnel carriers, and 4,472 artillery guns, including 375 self-propelled howitzers.
Despite its larger army, the capability of India's "conventional forces is limited by inadequate logistics, maintenance and shortages of ammunition and spare parts", IISS said in a report this month.
With 127,200 personnel and 814 combat aircraft, India's air force is substantially larger but there are concerns about its fighter jet fleet.
India's defence plans require 42 squadrons of jets, about 750 aircraft, to defend against a two-pronged attack from China and Pakistan.
With older Russian jets like the MiG-21, first used in the 1960s, retiring soon, India could have 22 squadrons by 2032, officials say.
Pakistan has 425 combat aircraft, including the Chinese-origin F-7PG and American F-16 Fighting Falcon jets.
It also has seven airborne early warning and control aircraft, three more than India, IISS said.
"The (Pakistan) air force is modernising its inventory while improving its precision-strike and ISR (intelligence, surveillance, and reconnaissance) capabilities," IISS said in its 2019 assessment.
India's navy consists of one aircraft carrier, 16 submarines, 14 destroyers, 13 frigates, 106 patrol and coastal combatant vessels, and 75 combat-capable aircraft.
It has 67,700 personnel, including marines and naval aviation staff.
Pakistan, which has a significantly smaller coastline, has 9 frigates, 8 submarines, 17 patrol and coastal vessels, and 8 combat-capable aircraft
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