Why the Administration would do this now, I have absolutely no idea. The last thing Obama needs is more backlash from the environmentalists in this country. Whales (as a species) aren't in any immediate danger from the remaining three holdout countries-- so the timing here is very likely part of a larger political strategy in U.S.-Japan relations.
Of course, I could be entirely wrong.
Whales as a whole endangered as species no but when you break it down in the various types of whales and look at which whales are hunted then it I gather it becomes a different matter.
Man nearly hunted the certain whale breeds to extinction in the 19th Century so the current numbers have taken a 100 hundred years to be reached.
The Japanese claim it's a historial and cultural part of their society - in which case they should be hunting the traditional way - which excludes the massive whaling ships and travelling to the Great Southern Ocean.
Tokyo's claim that it's a "treasured part of Japanese tradition and customs" is actually somewhat ridiculous. It doesn't employ that many people and it's not a source of great revenue. Whale meat is about as rare as say, escargot or frog legs in the United States-- and most people don't like it. In fact, whale meat tends to get stockpiled and given away to local governments. What you have here is a well connected special interest group tied into the Japanese propaganda machine.