Turkish President Recep Tayyip Erdogan later demanded action after protesters insulted the Quran, Islam's holy book, while enjoying Swedish laws on freedom of expression.
In an apparent but unstated sweetener, the United States jeopardized the sale of F-16 warplanes to Turkey, which has previously faced the wrath of US sanctions on large military purchases from Russia.
In January, the Biden administration approved US$23 billion in F-16 warplanes for Turkey following Sweden's membership confirmation.
The United States simultaneously pushed forward with USD 8.6 billion in more advanced F-35 jets for Greece, a fellow NATO member and historical rival of Turkey.
Even with Turkey's blessing, Sweden faced another hurdle as it needed the approval of the last country to visit – Hungary, whose nationalist prime minister, Viktor Orban, has often expressed his anger at Western allies.
The Hungarian Parliament confirmed Sweden's membership on 26 February. But in a final hurdle, Hungary could not sign the accession document due to a brief absence from the president's main ceremonial post, after an Orbán ally resigned over pardoning the partner of a convicted child abuser.
