This is a really crude fabrication - Bill Gertz reports "a senior Bush administration official tells us there are concerns that Russia will break out of its ban on testing nuclear weapons in the next two years".
First of all, Bill Gertz does not exactly have a reputation of an impartial reporter, especially when it comes to the issue of alleged Russian nuclear tests. A while ago Charles Ferguson documented a history of Gertz's false reports - "From early 1996 to late 1999, each of his reports on suspect Russian testing activities coincided with a CTBT-related political event." Why would anyone believe Gertz this time?
Then, "senior administration officials" have not been quite reliable with their estimates lately. Not to mention the bizarre nature of the estimate - why two years and not, say, one or three?
Of course, Russia is not exactly a model of transparency when it comes to things nuclear, but it's quite easy to see it's virtually impossible politically for it to be the first to resume nuclear tests. Besides, the Russian weapons people claim that they don't really need to test.