As a result, the Chinese Army has undergone significant changes in the past two decades. Active manpower has been slashed by several million troops. The number of field armies and combat divisions has been dramatically cut. At the same time, China’s rapid economic growth has allowed it to rapidly increase defense spending, funding high-tech upgrades.

Although the PLAGF lags behind China’s naval and air forces in priority, it has introduced a number of modern weapons systems. The Type 99 series of tanks has undergone several major revisions in the past decade, as the Chinese Army seeks to deploy a tank on par with the American M1 Abrams. The WZ-10, China’s first real attack helicopter, has begun to enter service. Despite the influx of new equipment, the PLAGF still counts vast amounts of obsolete equipment, such as Type 59 tanks in its active-duty inventories. Full modernization will take at least another decade, and possibly two, as the Chinese economy slows.

Rapid deployment forces are a key part of the PLAGF. PLAGF units could be called upon to operate on the border with India in the Himalayas, in the East and South China Seas or to invade Taiwan. In addition to armor and mechanized and infantry units earmarked for rapid response, the PLAGF has three airborne divisions, two amphibious divisions and three amphibious brigades. In addition, the divisions of the Shenyang Military Region may be called upon to secure the border with North Korea on short notice, or even intervene internally.

Indian Army:

At 1.12 million troops, the Indian Army is the second largest army in Asia. India, sandwiched between traditional rivals Pakistan and China, requires an army capable of defending long territorial boundaries. Native insurgencies and the requirement to conduct operations with the country of 1.2 billion people also pushes the country to a large, infantry-heavy force.

The Army’s best divisions are split among their four “Strike Corps”, with three such corps facing Pakistan and one facing China. India has two amphibious brigades, the 91st and 340 Infantry Brigade Groups, and also operates three airborne and eight special-forces battalions.

India’s Army has undertaken a considerable modernization effort over the last decade, primarily to improve its ability to operate conventionally against Pakistan. The so-called “Cold Start” doctrine, in which the Indian Army’s Strike Corps can execute a short-notice attack on Pakistan, requires a highly mobile army along Western lines. Indian-made Arjun and Russian-made T-90 tanks, alongside American-made AH-64 Apache helicopters will be expected to defeat the Pakistani Army before nuclear weapons could be employed.

The rise of China and what India has considered territorial violations along the Himalayan border between the two countries has prompted India to deploy an additional 80,000 troops—as many as the British Army in 2020—to its border with China.

Russian Ground Forces:

The Russian Ground Forces were formed from remnants of the Soviet Army. After the dissolution of the Soviet Union in 1991, many units were simply transferred to the Russian Army. Underfunded for decades, much of the Russian Ground Forces are still equipped with Soviet-era weapons. The Ground Forces are receiving, and projected to receive, an influx of new, modern equipment.

The Russian Ground Forces number 285,000, or roughly half of the U.S. Army. The Ground Forces are fairly well equipped and fully mechanized. Despite this, the sheer size of Russia (one soldier per 23 square miles of territory) means the Ground Forces are spread thin.

Despite their relative paucity, the Ground Forces have had considerable combat experience since the end of the Cold War, from ill-fated operations in Chechnya in the early 1990s to the current situation in eastern Ukraine.

The Russian Army inherited the Soviet Union’s airborne and marine forces, which by the mid-2000s, had been reduced from six to four divisions. At 6,000 troops, each division is light on manpower but highly mobile, equipped with BMD airborne infantry fighting vehicles. There are also roughly 9,000 naval infantry spread among Russia’s major fleets, although these are technically part of the Russian Navy.

The Russian Ground Forces are set to receive the Armata Universal Combat Platform in a few years’ time. A break from a present dominated by legacy T-72/80/90 tanks, BMP infantry fighting vehicles and BTR armored personnel carriers, Armata will be a whole new family of vehicles dedicated to the tank, infantry fighting vehicle, artillery and recovery vehicle missions.

The British Army

Although fairly small by global standards, the British Army is probably the most capable land force in Europe. Well rounded with a mixture of light infantry, airborne, tank, mechanized and aviation units, the British Army is capable of a broad spectrum of operations.

The British Army currently numbers 102,000 troops. The army is currently facing a reorganization by 2020 that will cut active duty manpower to 82,000 while increasing the role of army reservists. By 2020, the British Army’s deployable land forces will amount to seven brigades: one air assault, three armored/mechanized infantry and three infantry brigades.

Like the U.S. Army, the British Army relies on a legacy force of upgraded Cold War equipment. Challenger II main battle tanks and Warrior infantry fighting vehicles equip the mechanized forces. Although proven and reliable, these are getting on in age and will have to be eventually replaced at considerable cost.

The British Army’s special-purpose and special-operations forces are small, but among the best in the world. The British Army has three parachute battalions under 16th Air Assault Brigade plus the world-famous 22nd Special Air Service Regiment. An additional 8,000 Royal Marines, an infantry-centric force, operate under Royal Navy control and can deploy 3 Commando Brigade.

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Qualifying the five most powerful air forces in the world is certainly a difficult and challenging proposition. There are large, well-trained and well-equipped air forces that are obvious candidates for such a list. Then there are less-obvious candidates—like Russia. The Russian Air Force, while plane-for-plane older than many air forces, has numbers, the ubiquity of the largest country by size on Earth, a modernization plan and nuclear weapons. It cannot be ignored, and thanks to Putin and his repeated sorties near NATO and Japanese air space, it certainly won’t be. China is in many ways similar.

After that, however, the road gets murky. Vulnerabilities become apparent. There are air forces that are well equipped and trained, but for budgetary reasons, are too small to adequately fulfill national roles and requirements (think all of Europe.) There are also air forces that are magnificently equipped, but poorly trained. (Think virtually all of the Middle East.)

For the purpose of this article, we’ll judge air forces by the following criteria: size, influence and doing the best job of matching capabilities to the mission.

United States:

The U.S. Air Force

The preeminent air arm of the United States, the U.S. Air Force (USAF), is the primary service responsible for air and space missions. It manages everything from intercontinental ballistic missiles to X-37 space planes to A-10 Thunderbolt tank killers. It coordinates military space launches, airdrops of Army paratroopers and drops bombs on ISIS insurgents.

The USAF operates 5,600 aircraft of all types, including F-22 Raptors, F-35, F-15 and F-16 fighters. It operates B-2, B-1 and B-52 strategic bombers, as well as C-5, C-17 and C-130 airlifters. It operates these aircraft from bases in the continental United States and overseas bases from the United Kingdom to Japan.

The Air Force has roughly 312,000 active-duty members, coming in just behind the People’s Liberation Army Air Force, and yet it operates more planes than the PLAAF.

The USAF was the first air force worldwide to fly stealth combat aircraft, the first to fly fifth-generation fighters, and the first to commit to an all-stealth combat aircraft force. The USAF plans on preserving its edge by purchasing 1,763 F-35s and up to 100 optionally manned Long-Range Strike Bombers. Unmanned aerial vehicles, increasingly with stealthy profiles and attack capabilities, will gradually represent a larger proportion of the overall aircraft fleet.

The USAF also manages two legs of the U.S. nuclear triad, including 450 intercontinental ballistic missiles and the strategic bomber force.

The U.S. Navy and Marine Corps

Worthy of separate mention due to their size and capabilities, the U.S. Navy and Marine Corps are combined the world’s second-largest air force, with a total of over 3,700 aircraft of all types. This includes 1,159 fighters, 133 attack aircraft, 172 patrol aircraft, 247 transports and 1,231 helicopters.

The aircraft of the U.S. Navy are responsible for protecting the U.S. fleet and conducting air missions from and often over the world’s oceans and seas. Most of the aircraft of the Navy and Marine Corps operate from ships at sea, a difficult and dangerous job that requires a high level of training and proficiency.

The most visible aspect of U.S. naval aviation are the carrier air wings that fly off eleven nuclear-powered aircraft carriers. Each wing typically consists of around sixty aircraft divided into three squadrons of F/A-18 Hornets and Super Hornets, one E-2C Hawkeye airborne early-warning squadron, one EA-18G Growler electronic warfare squadron, and one helicopter squadron.