Key point: The role of navies worldwide has expanded in the past several decades to include new missions and challenges.

It’s a universal truth handed down since antiquity: a country with a coastline has a navy. Big or small, navies worldwide have the same basic mission—to project military might into neighboring waters and beyond.

The peacetime role of navies has been more or less the same for thousands of years. Navies protect the homeland, keep shipping routes and lines of communication open, show the flag and deter adversaries. In wartime, a navy projects naval power in order to deny the enemy the ability to do the same. This is achieved by attacking enemy naval forces, conducting amphibious landings, and seizing control of strategic bodies of water and landmasses.

The role of navies worldwide has expanded in the past several decades to include new missions and challenges. Navies are now responsible for a nation’s strategic nuclear deterrent, defense against ballistic missiles, space operations, humanitarian assistance and disaster relief. With that in mind, here are the five most powerful navies in the world.

United States

First place on the list is no surprise: the United States Navy. The U.S. Navy has the most ships by far of any navy worldwide. It also has the greatest diversity of missions and the largest area of responsibility.

No other navy has the global reach of the U.S. Navy, which regularly operates in the Pacific, Atlantic and Indian Oceans, as well as the Mediterranean, Persian Gulf and the Horn of Africa. The U.S. Navy also forward deploys ships to Japan, Europe and the Persian Gulf.

The U.S. Navy has 288 battle force ships, of which typically a third are underway at any given time. The U.S. Navy has 10 aircraft carriers, nine amphibious assault ships, 22 cruisers, 62 destroyers, 17 frigates and 72 submarines. In addition to ships, the U.S. Navy has 3,700 aircraft, making it the second largest air force in the world. At 323,000 active and 109,000 personnel, it is also the largest navy in terms of manpower.

What makes the U.S. Navy stand out the most is its 10 aircraft carriers—more than the rest of the world put together. Not only are there more of them, they’re also much bigger: a single Nimitz-class aircraft carrier can carry twice as many planes (72) as the next largest foreign carrier. Unlike the air wings of other countries, which typically concentrate on fighters, a typical U.S. carrier air wing is a balanced package capable of air superiority, strike, reconnaissance, anti-submarine warfare and humanitarian assistance/disaster relief missions.

The U.S. Navy’s 31 amphibious ships make it the largest “gator” fleet in the world, capable of transporting and landing on hostile beaches. The nine amphibious assault ships of the Tarawa and Wasp classes can carry helicopters to ferry troops or act as miniature aircraft carriers, equipped with AV-8B Harrier attack jets and soon F-35B fighter-bombers.

The U.S. Navy has 54 nuclear attack submarines, a mix of the Los Angeles, Seawolf, and Virginia classes. The U.S. Navy is also responsible for the United States’ strategic nuclear deterrent at sea, with 14 Ohio-class ballistic missile submarines equipped with a total of 336 Trident nuclear missiles. The USN also has four Ohio-class submarines stripped of nuclear missiles and modified to carry 154 Tomahawk land attack missiles.

The U.S. Navy has the additional roles of ballistic missile defense, space operations and humanitarian assistance/disaster relief. As of October 2013, 29 cruisers and destroyers were capable of intercepting ballistic missiles, with several forward deployed to Europe and Japan. It also monitors space in support of U.S. military forces, tracking the satellites of potential adversaries. Finally, the U.S. Navy’s existing aircraft carriers and amphibious vessels, plus the dedicated hospital ships USNS Mercy and USNS Comfort, constitute a disaster relief capability that has been deployed in recent years to Indonesia, Haiti, Japan and the Philippines.

China

The People’s Liberation Army Navy (PLAN) has come a long way in the last 25 years. The spectacular growth of the Chinese economy, which fueled a tenfold defense-budget increase since 1989, has funded a modern navy. From a green-water navy consisting of obsolete destroyers and fast attack boats, the PLAN has grown into a true blue-water fleet.

The PLAN currently has one aircraft carrier, three amphibious transports, 25 destroyers, 42 frigates, eight nuclear attack submarines and approximately 50 conventional attack submarines. The PLAN is manned by 133,000 personnel, including the Chinese Marine Corps, which consists of two brigades of 6,000 marines each.

The People’s Liberation Army Navy Air Force provides fixed-wing aircraft and helicopters for China’s new aircraft carrier, helicopters for surface ships, and shore-based fighter, attack and patrol aircraft. The PLANAF has 650 aircraft, including J-15 carrier-based fighters, J-10 multirole fighters, Y-8 maritime patrol aircraft, and Z-9 antisubmarine warfare aircraft.

China’s first aircraft carrier, the Liaoning, deserves special attention. It was commissioned into service in 2012. Originally built for the Soviet Navy, after the end of the Cold War, Liaoning’s unfinished hull languished in a Ukrainian shipyard. Purchased by a PLA front company, the ship was towed back to China where it spent nearly a decade being refitted. Liaoning is expected to function as a training carrier as China grows accustomed to the complex world of carrier operations.

The People’s Liberation Army Navy is well into the process of modernizing its amphibious capability, having commissioned three Type 071 amphibious platform dock ships. Each Type 071 LPD can carry from 500 to 800 Chinese marines and 15 to 18 vehicles, and can get troops ashore via hovercraft patterned on the American LCAC and Z-8 medium transport helicopters. China is also reportedly planning on building amphibious assault ships with full-length flight decks along the lines of the American Wasp-class. A total of six Type 071s and six of the new amphibious assault ships are rumored to be planned.

China’s submarine force is a decidedly mixed bag, with up to 60 submarines of varying quality. The core of the force consists of three Shang-class nuclear attack submarines, nine Yuan, 14 Song and 10 Improved Kilo submarines imported from Russia. China’s ballistic-missile submarine fleet is made up of three Jin-class missile submarines with a fourth (and possibly fifth) under construction. It is thought the South China Sea will eventually be used as a bastion for China’s sea-based nuclear deterrent.

The PLAN continues to grow and learn. At least two more aircraft carriers are planned, and China’s carriers could eventually number up to five. In addition to carrier operations, the PLAN is also learning how to conduct extended voyages through its contribution to the international antipiracy effort off the Horn of Africa. China has sent 17 naval task forces to the region, rotating in ships and crews to learn long-distance ship-handling skills.

Russia

Third on our list is the Russian Navy. Although traditionally a land power, Russia inherited the bulk of the Soviet Navy at the end of the Cold War. This aging force is at the core of the current Russian Navy, with more ships and fleet-wide improvements slowly being introduced. The Russian Navy has proven useful to show the flag and shore up flagging Russian power worldwide.

The Russian Navy has 79 ships of frigate size and larger, including one aircraft carrier, five cruisers, 13 destroyers, and 52 submarines. With the exception of a handful of attack and cruise missile submarines, virtually all of the Russian Navy’s combatants were built during the Cold War. Underfunded for decades, the Russian Navy faces chronic readiness problems. Large Russian ships such as the carrier Admiral Kuznetzov and the Pacific Fleet flagship Varyag are frequently accompanied by tugboats on extended voyages. It is unknown how many of the aging ships are actually seaworthy, and of those, how many are combat effective.

Russia also acquired the bulk of the Soviet Union’s amphibious capability. The fleet, a mixture of nearly two dozen Alligator and Ropucha landing ships, was constructed as far back as the 1960s, and is obsolete by modern standards. The purchase of two Mistral-class landing helicopter dock ships from France was meant to address that shortcoming, but the deal could be in peril due to Russia’s intervention in Crimea. However, at the present time, Paris seems to be holding to its commitment on the sale, a contract worth $1.6 Billion.

Like the Soviet Union before it, Russia’s naval strength is in its submarine force. Russia theoretically has 15 nuclear attack submarines, 16 conventionally powered attack submarines, six cruise missile submarines, and nine ballistic missile subs. Although some have been overhauled, nearly all of the submarines are of Cold War vintage and are of unknown readiness. The nine ballistic missile submarines represent Russia’s valuable second-strike nuclear capability and are probably at the highest readiness of any ships in the fleet.

Russia has big plans for its naval forces, but for the most part they remain just that—plans. Russia plans to acquire at least one more aircraft carrier, a new, unnamed class of guided missile destroyers, the Borey II ballistic missile submarines, Yasen II nuclear attack submarines, and the Improved Kilo and Lada conventional attack submarines. While the submarines are under construction, the aircraft carrier and destroyers are unfunded and exist only as blueprints.

This list catches the Royal Navy at a historic ebb in firepower. Like much of the British Armed Forces, the Royal Navy has seen successive waves of equipment and personnel cuts. The recent retirement of two Invincible-class aircraft carriers and the Sea Harriers of the Fleet Air Arm have greatly reduced the Royal Navy’s abilities. Nuclear firepower, as well as future aircraft-carrier plans earn it fourth place on the list.

The Royal Navy is the smallest on this list, with only 33,400 personnel on active duty and 2,600 in the reserves. The Royal Navy currently fields three large amphibious assault ships, 19 frigates and destroyers, seven nuclear attack submarines, and four nuclear-powered ballistic-missile submarines. The Royal Navy’s aviation force, the Fleet Air Arm, fields 149 aircraft, primarily helicopters.

The core of the Royal Navy’s surface force is its six Type 45 guided missile destroyers. Each destroyer of the Daring class is equipped with an advanced SAMPSON air tracking radar, similar to the SPY-1D radar of the U.S. Navy’s radar Aegis system. Paired with up to 48 Aster surface-to-air missiles, the destroyers can handle a wide spectrum of aerial threats, including ballistic missiles.

The Royal Navy’s submarine force has dwindled to less than a dozen submarines. The force of seven nuclear attack submarines is being upgraded by the introduction of the HMS Astute class. Astute and her sister ships carry Spearfish torpedoes and Tomahawk land attack missiles, and are among the most advanced submarines in the world. Four Vanguard-class ballistic-missile submarines constitute the U.K.’s nuclear deterrent. Each Vanguard weighs up to 15,900 tons submerged and is equipped with 16 Trident D II long-range ballistic missiles.

The Royal Navy will soon receive a quantum leap in capability with the construction of two new aircraft carriers, HMS Queen Elizabeth and HMS Prince of Wales. The two carriers, each weighing up to 70,000 tons fully loaded, will be the largest ships ever to sail in the Royal Navy. The carriers will each be capable of embarking up to 36 F-35B fighter-bombers and a number of helicopters.

Japan

The fifth navy on this list is unusual, because technically, it is not really a navy. Japan’s Maritime Self Defense Force (MSDF) is not a military force; its personnel are civil servants, not sailors. Largely under the radar, Japan has built up one of the largest, most-advanced and professionally manned naval forces in the world.

The MSDF has a total of 114 ships and 45,800 personnel. The core of the force is its large fleet of destroyers, designed to keep the sea-lanes to and from Japan from being cut as they were in the Second World War. This fleet of 46 destroyers—more than the British and French navies combined—has been expanded in recent years to accommodate new missions. Since the mid-2000s, the MSDF’s force of Aegis destroyers has been tasked with providing a defense umbrella against North Korean ballistic missiles.

Even more recently, Japan has constructed three so-called “helicopter destroyers”, each twice as large as the average destroyer with a strong external (and internal) resemblance to aircraft carriers. Indeed, these helicopter destroyers are carriers in all but name, designed to embark helicopters and—possibly in the future—F-35B fighter-bombers.

Japan has a modest, but growing amphibious capability. It has three tank landing ships of 9,000 tons that can move 300 troops and a dozen vehicles off-ship via helicopter and hovercraft. The helicopter destroyers can embark up to a battalion’s worth of marines from the new marine brigade to be based at Nagasaki, transport helicopters to carry them, and transport Apache attack helicopters to give them air support.

Japan’s submarine force is—ship-for-ship—one of the best in the world. There are 16 submarines in the JMSDF, the latest of the Soryu-class. Featuring an advanced air independent propulsion system, the Soryu submarines can remain submerged longer than other conventional submarines. The Japanese submarine fleet is young, with submarines retired at the average age of eighteen to twenty years. Japan has recently announced that the fleet would be increased to 22 submarines in response to the growing might of the PLAN.

Kyle Mizokami is a writer based in San Francisco who has appeared in The Diplomat, Foreign Policy, War is Boring and The Daily Beast. In 2009 he cofounded the defense and security blog Japan Security Watch. You can follow him on Twitter: @KyleMizokami. This article first appeared several years ago.

Image: Reuters.