Battlefields are constantly evolving, leading countries around the world to pump hundreds of billions of dollars each year into their armed forces in a race to develop the most advanced training, technology and weaponry.

As of 2020, Global Firepower, a website that tracks military strength, says the following five armies are the most powerful, based on a rank given to them after looking at how they compare in categories “ranging from military might and financials to logistical capability and geography”:

5) Japan

With an estimated active military personnel of 247,160, this Asian country only has a fraction of the headcount that volatile neighbor North Korea has, but makes up for it with its updated weaponry.

Japan has 152 special mission aircraft – more than any country in the world other than the U.S., according to Global Firepower’s statistics – and a formidable Navy fleet that contains 40 destroyers.

It also has 3,130 armored vehicles, 1,004 tanks and 119 attack helicopters.

Japan is estimated to spend $49 billion on its military in 2020.

Japan's armed forces have to contend with a volatile neighbor in North Korea. (iStock)

4) India

India, which has been engaged in a prolonged territorial conflict with nearby Pakistan over the Kashmir region, has an estimated 1,444,000 people actively serving in its armed forces.

Global Firepower says the developing nation is amongst the world’s leaders in the number of tanks (4,292), towed artillery (4,060) and fighter aircraft (538).

India is estimated to spend $61 billion on its military this year.

India has an estimated 1,444,000 people actively serving in its armed forces. (iStock)

3) China

China, the most powerful country in Asia and a growing adversary to the U.S., ranks third on this list.

The communist superpower has an estimated active personnel of 2,183,000 – the largest in the world.

China has been building out its Navy in recent years while engaging in territorial disputes across the South China Sea. Today, they have 74 submarines, 52 frigates and 36 destroyers, Global Firepower says.

On land, China has 33,000 armored vehicles and 3,500 tanks. Their Air Force has amassed 1,232 fighter aircraft and 281 attack helicopters.

China is estimated to spend $237 billion on its armed forces in 2020.

China, which has the largest active duty army in the world, is becoming a growing adversary to the U.S. (iStock)

2) Russia

Russia, whose military has become involved in Syria and Ukraine in recent years, has the most tanks of any country in the world: 12,950, more than double what the U.S. has, according to Global Firepower’s statistics.

Its estimated 1,013,628 active personnel, on land, are in charge of commanding 27,038 armored vehicles, 6,083 units of self-propelled artillery and 3,860 rocket projectors.

In the skies, Russia’s air force has 873 fighter aircraft and 531 attack helicopters. In water, they have 62 submarines and 48 mine warfare ships.

Russia is estimated to spend $48 billion on its military this year.

Russian soldiers stand near a convoy of rocket launchers in military parade rehearsal on Red Square, Moscow, in 2008. (iStock)

1) United States

In what shouldn’t be a surprise, the U.S. “retains its top spot as the undisputed military power in the world,” Global Firepower says.

America has more air units than any other country on Earth, with 2,085 fighters, 967 attack helicopters, 945 transports and 742 special mission aircraft.

The U.S. also leads the world with 39,253 armored vehicles, 91 Navy destroyers, and 20 aircraft carriers. It has an estimated 1,400,000 active personnel.

Washington has allocated $750 billion to the U.S. military budget in 2020.

The U.S., Global Firepower says, is the "undisputed" top military power in the world. (iStock)