As of March 31, 2020 (according to the U.S. Department of Defense via the 2021 World Almanac) there were 1,363,816 active duty military personnel (one of the lowest numbers in my lifetime).
Currently less than 5% (about 7,500) are serving in active war zones at any one time and this will be cut by 3,000 over the next month or so. There are an addition 849,000 or so personnel in the reserves.
This is only modestly above the post-World War II low. Even so, only two countries in the world have more active duty troops: China with 2,035,000 active duty and 510,000 reserves, and India with 1,456,000 active duty and 1,155,000 reserves, each of which has a population about three or four times that of the United States.
Several countries have more reserve troops than the U.S.: Russia with 900,000 active duty and 2,000 reserves, South Korea with 599,000 active duty and 3,100 reserves, Vietnam with 482,000 active duty and 5,000 reserves, Brazil with 367,000 active duty and 1,340 reserves, and Ukraine with 209,000 active duty and 900,000 reserves.
By Place Stationed
1,195,221 of U.S. active duty military personnel were in U.S. states and territories.
168,595 were stationed at foreign bases (excluding U.S. soldiers actively serving in Afghanistan and the Middle East in wars). By region (and in some cases further by country):
East Asia and Pacific 82,690
Japan 55,165South Korea 26,184Other East Asia and Pacific 1,341
Germany 34,574Italy 12,363United Kingdom 9,394Spain 3,227Turkey 1,702Belgium 1,142Other Europe 2,742
North Africa, Near East and South Asia: 10,273
United Arab Emirates 2,502Kuwait 2,016Other North Africa, Near East and South Asia 1,681
Western Hemisphere 1,976
Cuba (Guantanamo) 813Honduras 360Other Western Hemisphere 803
Sub-Saharan Africa 758
Former Soviet Union 197
According to a November 18, 2020 report from the BBC, by the time the President Biden takes office in January:
In Iraq, the number of US troops will be cut by 500 to 2,500, while the number of service personnel in Afghanistan will fall from 4,500 to about 2,500.
The number of active duty personnel in the major services of the U.S. military are above record lows, but only modestly:
The U.S. Army had 476,306 active duty personnel compared to a recent low of 466,990 in 2017, which was the lowest level since 1941.
The U.S. Navy had 339,782 active duty personnel compared to a recent low of 321,195 in 2012, which was the lowest level since 1941.
The U.S. Marine Corps had 182,729 active duty personnel compared to a recent low of 171,946 in 1995, which was the lowest level since about 1960.
The U.S. Air Force had 333,559 active duty personnel compared to a recent low of 312,195 in 2015, which was the lowest level since 1941 (prior to 1950 figures were for the U.S. Army Air Corps and Air Service of the Signal Corps).
The U.S. Coast Guard (which is not included in the figures above) had 41,798 active duty personnel compared to 27,695 in 2000 which the lowest since sometime before 1970.
Budgets and Major Weapons Systems
The U.S. military budget in 2020 of $685 billion was the largest in the world, with China at $181 billion in second place, and Saudi Arabia with $78 billion in third.
Foreign Policy magazine.
By comparison, "Sweden currently spends 1.1% of gross domestic product on defense. Guidelines issued by NATO, of which Sweden isn’t a member, advise that members spend 2%, although many do not achieve that target." Sweden just approved a 40% defense budget increase to address rising Russian Naval aggression in the Baltic Sea.
Main Battle Tanks
The U.S. has 2,389 main battle tanks in the Army. A number of other countries have more including: China 5,850, India 3,565+, North Korea 3,500+, Russia 2,800, Pakistan 2,433, Egypt 2,480, and Turkey 2,379.
Air Force Resources
The U.S. has 271 air force combat aircraft classified as fighters and 969 classified as fighter ground attack in its Air Force (and more in the Navy and Marines). In the U.S. case, the air force fighters are F-15s and F-22s, while the fighter ground attack category includes A-10s, F-16s and F-35s.
Two countries have more in one or both categories: China 759 fighters and 794+ fighter ground attack, North Korea 401+ fighters and 30 fighter ground attack. Of course, raw numbers don't necessarily accurately convey strength as the quality of different combat aircraft varies greatly.
This data doesn't tell of story of long range bombing capabilities or naval aircraft.
The U.S. has 20 aircraft carriers (11 "super carriers" of 100,000 tons or more, and 9 amphibious assault ships which can carry helicopters, Osprey aircraft, Harrier aircraft or F-35B aircraft of 40,000-45,000 tons), 67 destroyers, 24 cruisers, 19 frigates (for a combined 110 surface combatants excluding aircraft carriers) and 67 military submarines.
The U.S. does not have a battleship class ship. Russia, with two 28,000 ton ships, only one of which is in active service, is the only country in the world that does. It also has three 12,500 ton cruisers. The largest surface combatant in U.S. service is the 14,564 ton Zumwalt class destroyer (widely acknowledged to be a dud). There are no other surface combatants (that are not aircraft carriers) of more than 10,300 tons in the world.
Some of the other countries with the most military submarines are North Korea 73, China 59, Russia 49, South Korea 22, Japan 21, Iran 19, India 17, Turkey 12, Pakistan 8, Vietnam 8, Egypt 6, Germany 6, and Israel 5, Brazil 5, Columbia 4. Quality, of course, is an issue here. Only a few of these countries have "blue sea" submarines as opposed to diesel powered coastal submarines. Many of these are inferior models.
As of November 5, 2019 only twenty navies in the world had surface warships (including aircraft carriers, but not transport ships) larger than a frigate: U.S. (111), Japan (48), China (33), Russia (20), India (14), France (14), United Kingdom (7), Norway (5), Italy (4), Taiwan (4), Netherlands (4), Denmark (3), Germany (3), South Korea (3), Egypt (3), Saudi Arabia (3), Spain (2), Brazil (1), Thailand (1), and Morocco (1).
Currently, the U.S. has 20 aircraft carriers (11 "super carriers" of 100,000 tons or more, and 9 amphibious assault ships which can carry helicopters, Osprey aircraft, Harrier aircraft or F-35B aircraft of 40,000-45,000 tons), Italy has 2, Japan has 4, France has 4, Australia has 2, Egypt has 2, and Brazil, China, India, Russia, Spain, Thailand and the United Kingdom each have one. In all there are 42 aircraft carriers in active naval service in the world.Five aircraft carriers (one each from the U.K., China, Russia, India and France in order of size) are between the size of a U.S. super carrier and the smallest U.S. amphibious assault ship ranging from 42,000 to 65,000 tons (and only four of these from the China, Russia, India and France, and the ten U.S. super carriers, allow for something other than a vertical landing). The other eighteen aircraft carriers range from 11,486 tons to 27,100 tons (eleven of which are restricted to vertical takeoff and landing aircraft such as helicopters and the MV-22 Osprey). All twenty-seven carriers under 42,000 tons and two larger aircraft (one from the U.S. at 45,000 tons and one from the U.K. at 65,000 tons) are restricted either to short takeoff vertical landing aircraft such as an F-35B or a Harrier, or to vertical takeoff and landing aircraft.Eleven more carriers (including two that are only VTOL carriers) are undergoing sea trials or ordered: the U.S. 3, China 3, and South Korea, India, Italy and Turkey one each.Currently, the U.S. has 22 cruisers (10,000 tons each) and Russia has 4 (one battleship with 28,000 tons and three cruisers with 12,500 tons) in active service. In all there are 27 cruisers in active naval service in the world. The U.S. cruisers are virtually indistinguishable from its destroyers and slightly inferior to them as they are older designs.Currently, the U.S. has 69 destroyers (including 2 of the Zumwalt class), Japan has 44, China has 32, Russia has 15, India has 13, France has 10, the U.K. has 6, Norway has 5, Taiwan has 4, the Netherlands has 4, Germany has 3, Denmark has 3, South Korea has 3, Saudi Arabia has 3, Italy has 2, Egypt has 1, Morocco has 1, and Spain has 1. The largest destroyer in active service (other than the two Zumwalt class destroyers in active service) is 10,290 tons and many of which are considerably smaller. Some of the destroyer class ships are larger, more capable ships actually called frigates in an effort to make comparisons comparable. All ships classified as frigates for these purposes are under 5,000 tons, although a few particularly capable frigates between 4,000 and 5,000 tons are classified as destroyers. There are 219 destroyers in all of the world's navies combined.
The U.S. is one of a handful of countries with nuclear weapons and has the largest stockpile of them with the possible exception of Russia.