Hungary’s president on Tuesday formally signed a bill approving Sweden’s NATO bid, removing the last obstacle after 18 months of delays that frustrated the alliance as it sought to expand in response to Russia’s war in Ukraine.

President Tamás Sulyok’s signature was needed to put into force a bill that was passed in Hungary’s parliament last month in a culmination of months of wrangling by Hungary’s allies to convince its nationalist government to lift its block on Sweden’s membership.

“It is incredibly positive,” Swedish Defense Minister Pål Jonson said in Stockholm. He told his visiting German counterpart Boris Pistorius: “You really come at a historic time for Sweden as we are about to become full fledged members of NATO.”

“That decision will make Sweden safer and NATO’s stronger,” said Jonson.

Pistorius said he was “delighted because at last, good friends turn into allies as members of NATO, and we are welcoming you with open arms to this important alliance.”

The government of Hungary’s Prime Minister Viktor Orbán first submitted the protocols for approving Sweden’s entry into NATO in July 2022, but the matter stalled in parliament over opposition by governing party lawmakers.

Hungary’s decision paved the way for the second expansion of NATO’s ranks in a year after both Sweden and Finland applied to join the alliance in May 2022 following Russia’s full-scale invasion of Ukraine — an assault that was purportedly intended to prevent further NATO expansion.

Unanimous support among NATO members is required to admit new countries, and Hungary was the last of the alliance’s 31 members to give its backing since Turkey ratified the request in January.

Orbán, a right-wing populist who has forged close ties with Russia, has said that criticism of Hungary’s democracy by Swedish politicians soured relations between the two countries and led to reluctance among lawmakers in his Fidesz party.

Sulyok took office on Tuesday, following the resignation of President Katalin Novák, who stepped down last month in a scandal over her decision to pardon to a man convicted of covering up a string of child sexual abuses.

Sulyok is a former president of Hungary’s Constitutional Court. The endorsement of Sweden’s NATO bid was his first act as president.