History Spotlight, 2/6

A classic case of "nations only obey treaties until they become inconvenient," the Washington Naval Treaty was signed on February 5, 1922 in Washington, DC. In this case, it lasted about a week.
The treaty itself came about from the spasm of international unity following World War I. At the time, Britannia still ruled the waves, but the US was coming up fast on her stern with Japan in a distant third place but also coming on strong. Britain wasn't too worried about the US and the US, for its part, wasn't worried about Britain, but they were both worried about Japan. While it's true that, at the time, Britain had a mutual defense pact with Japan nobody in His Majesty's government or in the Emperor's court thought this was anything but a temporary alliance of convenience. Also along for the ride were France and Italy because, well, why not - they both still had the imprateur of being world powers.
The treaty had two main purposes, one which was known to all parties and one which was not. The first, known, point of the treaty was to limit the size of a nation's navy in order to encourage the peaceable use of the sea lanes. The second purpose, known only to the US and Britain, was to limit the size of the Japanese navy, which was already being viewed as a threat. What was even more unknown, even to the British, was that the US intelligence service had been listening in to all of the delegates conversations with their respective governments and knew exactly where each nation's deal-braking point was.
The terms of the treaty itself aren't really that interesting: none of the signatory nations could have a ship over 35,000 ton and none of the ships guns could be larger than 16 inches in diameter. The weight restriction did not include fuel or water for boilers. Britain lobbied hard for this point because of their globe-spanning empire. An additional limitation was placed on the new aircraft carriers that were coming out: no nation was to have more than two carriers over 27,000 tons.
What's more interesting is the lengths the signatory nations went to get around the treaty:
The US used new boiler designs to get a faster ship in a smaller frame. It also built a fleet of carriers that came in just under the weight limit.
Britain built ships that could have additional armor added in the event of war.
Germany, while not a signatory to the treaty, was still bound by the limitations imposed by the Treaty of Versailles. They used a new form of high-strength steel to put more armor in a lighter package.
France pouted and complained that the treaty was unfair.
Italy lied about their ships' tonnage.
Japan withdrew from the treaty in 1936 and, really, never had any intention of following it anyway.
In the end, there were five (six, if you count Germany) nations either following the letter of the treaty but not the spirit or completely ignoring the treaty. By the time World War II rolled around, it had been tossed in the trash.