The worst oil spill in US history

I keep seeing the Gulf oil spill referred to in those terms. But, since the oceans are all interconnected and, since the clean-up effort itself is causing additional pollution -- both in the water and in the air -- which itself is likely to spread far and wide, shouldn't we be calling it the worst oil spill in the history of the world?

Or are we afraid that, if we acknowledge the broader effects of the disaster, we might get sued by Mexico, Europe, and God-knows who else when our oil washes up on their shores, when our plume of smoke from burning off the oil reaches their air space?