The purpose with this study is to investigate how the two biggest political parties, the Social Democrats and the Moderate/Conservative Party, looks at a membership in the defense alliance North Atlantic Treaty Organization. The question have the illegal annexation of Crimea affected how the parties look at a membership in Nato will be answered and analyzed. How they discuss, how they believe that a membership can affect the Swedish foreign policy will be examined in this paper.   Nato is a topic that during the last century’s have divided the Swedish population into two groups: one that advocates a membership and one that fight’s against a Swedish membership in the alliance. The debate about Nato has, since the illegal annexation of the Crimea, changed and are now more relevant than ever to discuss. This paper illustrates how the Moderate/Conservative Party and the Social Democrats argues in the debate regarding a membership in Nato.   Since 2003 the Moderate/Conservative Party are in favor of a membership in the defense alliance Nato, what this paper will find out is why they want Sweden to become a member in Nato and how they argue for a membership. The Social Democrats are not in favor of a membership in the defense alliance, they advocates the defense line Sweden have had since the mid 1900s, the Non-alignment.