Is it possible to justify the size of the US navy?

[Yarn]

The U.S. Navy is the largest in the world; its battle fleet tonnage is greater than that of the next 13 largest navies combined.[4] The U.S. Navy also has the world's largest carrier fleet, with 11 in service, one under construction (two planned), and one in reserve. The service had 328,516 personnel on active duty and 101,689 in the Navy Reserve in January 2011. It operates 286 ships in active service and more than 3,700 aircraft.[2]

United States Navy - Wikipedia, the free encyclopedia

Also factor in the fact that any war with another major power is certain to be nuclear, meaning these ships are useless when it comes to China and Russia, and that the size of our navy doesn't tell the whole story because we also have the best technology, and I really can't comprehend why we need such a large navy. Can any of you?

[Senor Hoint]

Unless you believe the United States has the right to engage in imperialism across the globe, no, not really.

[sulh-i-kul]

The US government stands openly in contempt of international law. Might makes right.

The US is not quite as large as it sounds since there most of these 13 navies are not competing navies. Most governments have realized there is no point in trying to compete with the US navy. A few still induldge or pretend to but from the oceans, it indeed looks like a unipolar world.
The US navy may be pointlessly expensive and sophisticated and maybe even too large considering the extensive network of US bases across the world but there's a point in having a large navy.
The main point is not to sink other navies. This is best done with missiles which can be fired from long-range aircraft if need be. The main points are to enable invasions and to control civilian shipping. The US navy would for instance be able to blockade China. Its economic power is tremendous.

[Yarn]

Blockading China would get us nuked or at the very least they would take out our ships with missiles that can penetrate any missile shield and have a range of more than a 1000 miles. It would also ruin the economy because they could likely take out the internet, and anyways our trade volume with them is huge.

The US navy protects freedom of the seas (is this a possible adequate justification, or Somalia aside, would the seas be safe with or without our navy being as big as it is?).

Invasions make a certain amount of sense, but a small fraction of the navy is sufficient to service that end.

[sulh-i-kul]

The US Navy doesn't have to come within 1000 miles of China to blockade it effectively.
By arguing that China would initiate the use of nuclear weapons against a superior foe over the behavior of the US navy (I don't believe that), you're acknowledging it is an existential threat to China. As such, its strategic value is huge.

"take out the Internet" <- ?

[Yarn]

Nuclear weapons produce mutually assured destruction. They are neither a superior nor inferior opponent when it comes to nukes, no one with an adequate number of them with effective delivery mechanisms is. China maintains enormous numbers of highly competent hackers under state control, and the US is a very vulnerable target in that regard because we rely on the internet more than perhaps any other country in the world. It is a commonly believed maxim that it doesn't matter how good your security is, if you are linked to the web and the entity attacking you has adequate resources, any site can be compromised because no security system is invulnerable.

[Angry Citizen]

Our enormous Navy is one of the things I would keep if I were able to remake the United States in my image. It's the Army and Marines that I would downsize. Power projection is important. The mere presence of a CBG can calm tensions without a shot being fired.

[Yarn]

Maybe. It isn't as expensive as I would've thought. It is around 160 billion dollars per annum, as of the latest budgetary request.

[JimmyNic]

Unless you believe the United States has the right to engage in imperialism across the globe, no, not really.

Haha, rights. Good one.

One thing worth noting is that I suspect a portion of the navy is part of the nuclear weapons programme; Britain has at least 3 nuclear submarines that contain the lion's share of our nuclear payload. I suspect the US has a more land based scheme, but it's worth thinking about. It's also linked in with the airforce and the army, so I'd say viewing the navy in isolation is a mistake. After all there is little point having a large army without the means to transport them to the theatres of war. I guess whether or not you consider the cause justifiable depends on what you believe the point of the armed forces is.