The US is hardly the only First World nation which regards the actual text of its Constitution as a bit of an inconvenience. Japan does the same thing (perhaps rather appropriately, since we wrote it for them). Article 9 of Japan’s Constitution prohibits development of an “offensive” military capacity, hence the reason its rather large and capable navy is labeled a “Maritime Self-Defense Force”. It is, admittedly, not a force suitable for offensive action against any first-rank naval power (the US, the British, or the Russians), since its lack of aircraft power means that its ships would be very vulnerable outside the umbrella of land-based Japanese air protection. So in force composition, that makes it nominally constitutional even though its large, modern, very professional force is enough to pose a serious naval deterrent to China.
Overseas deployments are, however, almost certainly not kosher. That’s why Japan dodged out of the Gulf War and instead deployed only a large check to the region. Yet in 2004, the Japanese deployed troops to Iraq. Albeit on a “humanitarian” mission, this still dove face-first into a thicket of legal issues which have not really been addressed. And now the Japanese are sending warships to shoot pirates off the Somali Coast. While one is tempted to say that the Japanese can’t have it both ways, that’s really just sour grapes. I think their strategic posture is pretty sensible. Their officially pacifist stance defuses what would otherwise be very tense Sino-Japanese relations, and allows the Japanese to avoid the hazards of international politics. Yet they are protected by the United States nuclear umbrella.
Basically, they can have their cake and eat it too, thanks to unchallenged American global hegemony. Bright guys.