One reason has to do with today's global power scheme. The US is a lone superpower and has capable fleets in both the Atlantic and the Pacific. In the case of the Panama Canal, Navy officials say cross-ocean ship movement is no longer crucial enough to justify military control of the waterway. Meanwhile, across the Atlantic, Europe is uniting and expanding, and internal rivalries are no longer fought on the seas. Moreover, throughout the world, militaries increasingly project power by air.
Oil is transported by pipeline.
And information is bounced off satellites well above the earth's waters. It was not until the first decade of the 1900s that modern naval strategy recognized and emphasized the importance of a handful of narrow waterways - which, if controlled, could result in disproportionate power. Then, Britain ruled the seas, but it was facing increasing competition. Sir John Fisher, the commander in chief of the Royal Navy, began to transform Britain's fleet from stationary to mobile. But well before Sir John pinpointed his country's strategy, most choke points had histories of war and conquest, and were won and lost with the ebb and flow of global dominance.