NATO chief Jens Stoltenberg on Sunday urged Ankara to drop its opposition to Sweden's bid to join the US-led defense alliance. 

"Membership will make Sweden safe but also make NATO and Turkey stronger," Stoltenberg said in Istanbul. "I look forward to finalizing Sweden's accession as soon as possible." 

Stoltenberg visited Turkey over the weekend to attend President Recep Tayyip Erdogan's lavish inauguration ceremony on Saturday, as the leader of two decades (either as prime minister or later as president) formally starts his third term as president. 

He also held talks with Turkey's new foreign minister, Hakan Fidan, who replaces longstanding top diplomat Mevlut Cavusoglu in Erdogan's reshuffled Cabinet.

'Sweden has taken significant concrete steps' 

Turkey claims to object to Sweden's membership, as it previously opposed Finland's, because the countries harbor people it considers terrorists. These individuals are often Kurdish activists with alleged ties to the separatist Kurdistan Worker's Party (PKK),  blacklisted by Turkey and many of its Western allies. 

"Sweden has taken significant concrete steps to meet Turkey's concerns," Stoltenberg said, referring to the recent introduction of tougher laws concerning support for terrorist organizations in Sweden, and Stockholm's increased counter-terrorism cooperation with Ankara. 

Erdogan had made it clear during the heated campaign that he was unlikely to make a decision on Sweden prior to securing re-election, which he did in a narrow run-off vote one week ago. 

Finland and Sweden elected to leave a path of decades of military non-alignment, which lasted throughout the Cold War, behind them in response to Russia's invasion of Ukraine. 

Why is Turkey digging its heels in? 

Although Turkey dropped its objections regarding Finland earlier this year, various public protests in Sweden critical of Erdogan, his government and Islam — probably caused at least in part by Turkey's initial resistance — appeared to anger Ankara further. 

Sweden's government on Saturday permitted another protest that Ankara had formally objected to, under the motto "No to NATO, No Erdogan Laws in Sweden," organized by groups close to the PKK. It took place on Sunday.

Stoltenberg said that while he understood that it was "hard to see demonstrations against Turkey and against NATO in Sweden," he urged the Turkish government to "remember why these demonstrations are taking place."

"The organizers want to stop Sweden from joining NATO. They want to block Sweden's counterterrorism cooperation with Turkey, and they want to make NATO weaker. We should not allow them to succeed," he said. 

Why is Turkish approval needed? 

Prospective NATO members must be approved by the legislatures of all existing NATO member states in order to join the alliance. Lawmakers in Turkey and Hungary — the same two countries that were last to approve Finland — are yet to hold votes on Sweden.

Hungarian Prime Minister Viktor Orban was another Western leader to attend the weekend ceremony in Istanbul, while many major Western NATO powers sent more minor officials. Both Hungary and Turkey have stood out among NATO's 31 members since Russia's invasion of Ukraine as the two countries still trying to maintain comparatively cordial ties with Moscow.

Former German President Christian Wulff was sent by the government in Berlin, although ex-Chancellor Gerhard Schröder was also in attendance, while the US sent its Turkish ambassador.

Sweden, meanwhile, sent Carl Bildt. On the face of it, he too is "merely" a former prime minister. However, he's also arguably Sweden's best-known and most accomplished diplomat — a foreign minister before becoming prime minister and a key negotiator in the Balkan wars of the 1990s before that.

msh/nm (AFP, AP, dpa, Reuters)