Thanks to America’s global network of interests and alliances, the Navy’s area of responsibility is for all intents and purposes the entire planet, with very few bodies of water off limits. From the Black Sea to the Yellow Sea, the Navy is expected to show the flag—or fight—around the world.
Such a vast area of responsibility also means that the U.S. Navy has to be able to prevail against an equally vast array of threats. From the low-tech speedboats and mines of the Iranian Navy to the high-tech antiship ballistic missiles of the People’s Republic of China, the Navy must be prepared to deal with them all. Here’s a roundup of five of the greatest threats.
One of the most vexing threats to the U.S. Navy is decidedly low-end: sea mines. First invented in the fourteenth century by a Chinese artillery officer, sea mines occupy a peculiar place on the threat spectrum: easy to ignore in peacetime, but quickly one of the most pressing for an expeditionary navy in wartime.
In the last thirty years several American ships have been struck by mines, including the frigate Samuel B. Roberts, guided missile cruiser Princeton and the amphibious assault ship Tripoli. All in all, several billion dollars’ worth of combat ships sidelined by what was probably no more than half a million—if that—in sea mines.
America’s potential adversaries maintain a robust mine inventory. China is estimated to have  from fifty thousand to one hundred thousand mines of all types, and Iran is estimated to have “several thousand .” Despite its aversion to dealing with them, in any future conflict the U.S. Navy will almost certainly have to go to where the mines are.
Antiship Ballistic Missiles
Capitalizing on the country’s large rocket force, China has developed intermediate-range ballistic missiles designed to attack warships, particularly aircraft carriers. Although both antiship missiles and ballistic missiles have both existed for decades, the combination of two has created an entirely new threat really unlike any that has existed before.
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The development of the DF-21D and now DF-26  missiles is a major new threat to navies that wish to operate in waters adjacent to the Chinese mainland. The two missiles are a major component of China’s “anti-access, area denial” strategy, meant to create no-go zones in the western Pacific. It must be assumed that at some point China will export the technology, to countries such as Russia or North Korea, and that ASBMs will eventually be a worldwide threat.
The U.S. Navy de-emphasized antisubmarine warfare after the end of the Cold War, and the emphasis on land operations following 9/11 further eroded the Navy’s sub-hunting capabilities. The retirement of the S-3 Viking, the delayed replacement of the P-3C Orion, the lack of new shipboard antisubmarine sensors and weapons, and the loss of institutional experience in ASW have all been understandable opportunity costs borne of a lack of enemies.
In the last four to six years, however, the submarine threat has taken on a greater level of urgency. The governments of China and Russia are not only growing more aggressive but are growing their sub fleets. North Korea appears determined to field a ballistic-missile submarine complete with a submarine-launched ballistic missile. Antisubmarine warfare has returned.
Supersonic Antiship Missiles
Ship-to-ship warfare is another realm of naval warfare that took a back seat for a quarter-century, only to come roaring back. Antiship missiles are again proliferating worldwide, faster and more lethal than ever.
China’s YJ-18 antiship cruise missile  has an estimated range of 290 miles and a terminal phase speed of Mach 2.5 to Mach 3. Russia has developed the joint Indian-Russian BrahMos antiship missile capable of Mach 3, and although it hasn’t fielded the weapon, Russia clearly could do so.
The range of weapons like the YJ-18 will vastly increase the amount of real estate the Navy must monitor—and prepare to sink ships and submarines in—to preempt enemy forces. The alternative is to deal with the missiles once launched, and with a speed of Mach 3 and, in the case of BrahMos, a flight altitude of fourteen meters, there will be very little time to deal with an incoming threat.
Just as the introduction of the guided missile ushered in an entirely new era of warfare, increasingly it appears so will the laser. Although some ways off, the fielding of directed-energy weapons by America’s adversaries will be a grave threat—and an eventuality. All of the great advantages heralded by the Pentagon regarding laser weaponry—quiet and largely invisible, the low cost per shot, the inability to dodge a weapon moving at the speed of light— would also apply to the lasers of our adversaries.
Russia and China are undoubtedly working on laser technology, and from there, lasers will become commonplace. Like antiship missiles, even nonstate actors will someday possess them. What will be the effect on U.S. forces when AMRAAM missiles can be burned out of the skies, ships close to shore are attacked with laser beams, and antiship missiles are targeted by laser weapons that can take multiple shots at the same target in a matter of seconds?