In the course of the past months NATO has changed rapidly. Whereas during the two decades after the end of the East-West-Conflict defence of the alliance was hardly emphasized, the issue of collective defence has become important for the Allies since the beginning of the Ukraine-Crisis 2014 and the subsequent repetitive demonstrations of Russian military power in the Baltic States and in the Baltic Sea. The East-European Allies, above all the Baltic States and Poland, have insisted on a stronger focussing on defence of the alliance since their joining NATO 1999 and/or 2004. In the case of Germany, a series of surveys verifies that this reorientation in its consequences has not found a majority in the population so far. Additionally, Germany takes up a special attitude in the study, published in June 2015 by the US Pew research Center, on the public attitude of eight NATO nations towards the importance of Atlantic alliance solidarity. 58% of the interrogated people – more than 10% of the average – stated that they would not favour military support of a NATO partner in the case of Russian aggression. Already in the beginning and further development of the Ukraine Crisis, the majority of the German population expressed scepticism against an increased military role of NATO in the territories of its eastern members. According to a study of April 2015, almost half of the interrogated people (49%) claimed that Germany ought to take up a mediative role between Moscow and the West. Moreover, a majority of the political elite do not force themselves to distinctly explain to the public how Russia’s shifting of borders within Europeen dangers stability on the continent in general and territorial integrity of the eastern NATO members in particular. Against this background the question arises how Germany will be able to meet the increased expectations concerning its security-political role if the public reject taking over more military responsibility. The object of this essay is investigating which the consequences of a decreasing (public) declared belief in NATO alliance solidarity can be for progressing defence-political integration. With the German example as well with one of the eastern allies – especially Poland– people argue that such a climate of public opinion could have a negative effect on military co-operations. There are, however, eminent examples for “pooling and sharing” which are, regardless of public opinion, absolutely successful. It is also important to point out that, apart from public opinion, there is a multitude of parameters which influence defence-political projects. For this reason one must not overvalue the public opinion concerning alliance solidarity inGermany: Public opinion – which can only partly be illustrated by surveys – cannot be compulsively equated with the attitudes of the Federal Government. In the course of recovery of collective defenceGermanyhas explicitly committed to its alliance obligations in the framework of NATO several times. Thus,Berlincontinues a NATO policy which mostly corresponds with the guidelines of the past 25 years: the commitment to and emphasis on collective defence. Additionally, in case of emergency governments often act against public opinion, if the security-political interests of the country require it. It is, however, still a political necessity to convince the own population of the central value of alliance solidarity together with its political and military suppositions and consequences. Only in this manner the deterring effect of the alliance can be made plausible abroad and a renationalisation of security and defence politics at home can be prevented. If security politics is not supported by at least the majority of the population, it will be neither credible nor resilient.