This article was linked in the comments. I will not link to it for legal reasons, but you should be able to look it up easily.
I'd like to offer a quick hint that reveals how the author totally did not do his homework and in fact wrote an article that mostly and as a whole made no sense whatsoever because of this ignorance.
Article IIEach non-nuclear-weapon State Party to the Treaty undertakes not to receive the transfer from any transferor whatsoever of nuclear weapons or other nuclear explosive devices or of control over such weapons or explosive devices directly, or indirectly; not to manufacture or otherwise acquire nuclear weapons or other nuclear explosive devices; and not to seek or receive any assistance in the manufacture of nuclear weapons or other nuclear explosive devices.
An anecdote was leaked years ago that French then-president Sarkozy had proposed (in a meeting with chancellor Merkel) a binational control over French nukes as one of his erratic ideas and got angry when German minister of foreign affairs shot the idea down pointing out the NPT. I suppose a Spiegel journalist and his editor should have been aware of this part of the NPT since that leak at the latest.