Treaty on the Final Settlement with Respect to Germany
September 12, 1990ARTICLE 3
(1) The Governments of the Federal Republic of Germany and the German Democratic Republic reaffirm their renunciation of the manufacture and possession of and control over nuclear, biological and chemical weapons. They declare that the united Germany, too, will abide by these commitments. In particular, rights and obligations arising from the Treaty on the Non-Proliferation of Nuclear Weapons of 1 July 1968 will continue to apply to the united Germany.
It's seems to me that there's an obvious and probably intentional loophole, since the NPT did continue to apply after the reunification of Germany, but the Final Settlement doesn't say it will continue to apply forever.
We call that treaty the "2+4"-treaty (German Dem. Rep., Fed. Rep. of Ger. + France, UK, USA, SU). And I don´t see a loophole here. The treaty gives Germany its full sovereignty back, so why shouldn´t we be able to change the treaty by a notification and the consent of the 4 former occupation powers? We´re definitely not going to get nukes without the consent of our most important allies... for now. :)