Russia’s invasion of Ukraine turned the spotlight on Turkey’s status as a regional power. Sweden and Finland’s expected bid to join NATO could further boost Turkish influence if the concerns raised by Turkish President Recep Tayyip Erdogan, who noted his objection to possible Swedish and Finnish membership in the US-led alliance, could be addressed.

There are several reasons for Turkish objections to NATO’s expansion into Sweden and Finland.

First, in the wake of Turkey’s purchase of the S-400 air defense system from Russia in 2019, the United States removed Turkey from the F-35 fighter jet program. By acquiring some 120 F-35s through the early 2030s, coupled with the introduction of the locally designed and manufactured “National Combat Aircraft,” Turkey would have become the preeminent air power in its neighborhood. 

Ankara also lobbied its allies to purchase advanced air defense systems for years — especially the US-made Patriot missiles. In the mid-2010s, various NATO allies sent their Patriot batteries to protect Turkey’s Syrian border. The withdrawal of US air defense forces in 2015 at one of the most critical junctures of the Syrian conflict offended the Erdogan administration. Under Article 5 of the Washington Treaty that established NATO in 1949, member states pledge to come to each other’s defense in times of war.