NATO is, at its core, a military alliance, whose members increasingly recognize the role that Turkey could play in its future, as concerns grow over the war in Ukraine and President Trump’s threats to reduce the U.S. role in the organization, or withdraw from it altogether.

Advocacy groups say that Turkey’s newfound importance to NATO has led member states to remain silent as Mr. Erdogan pursues a path toward greater autocracy.

“Turkey is so much more offside than any other NATO state with respect to democracy and human rights, and that should be a glaring difference for other countries,” said Emma Sinclair-Webb, the Turkey director for Human Rights Watch. “NATO member state leaders should look over the wall of the palace and see what is going on in the country.”

The two-day summit in Ankara, the capital, is expected to address the defense budgets and military industrial capacity of NATO countries. Governance inside member states is not on the meeting’s agenda and is unlikely to be discussed publicly, although the preamble of the alliance’s founding treaty says that its members are dedicated to the “principles of democracy, individual liberty and the rule of law.”

The Turkish government has repeatedly said that its legal system is free from political interference, and Mr. Erdogan has said that his political opponents are to blame for their legal troubles.

The Turkish authorities did not cite the NATO summit in connection with the wave of arrests, although some of them appeared to be aimed at preventing disturbances during the event.

The Ankara prosecutor’s office said last month that the police had detained 225 people and that 103 of them had been sent to pretrial detention during a security operation “to expose the activities of terror organizations around the country.”

Those detained included members of leftist groups that have staged protests in the past. They also included over a dozen environmental activists, an associate professor of political science at Ankara University, the editor of an L.G.B.T.Q. magazine and Deniz Goktas, a 32-year-old comedian.

Mr. Goktas’s routines have taken an edgy approach to politics and religion in Turkey, an overwhelmingly Muslim country with a constitutionally secular government. In one gag, he muses about Mr. Erdogan possibly going to therapy, saying that the president had gone from being a “shy dictator” to a “more-at-peace-with-himself dictator.”

In another, he refers to an episode in 1998, when Mr. Erdogan was the mayor of Istanbul. A woman died after Mr. Erdogan’s elder son, Burak, hit her with his car. Burak Erdogan told prosecutors that he was not at fault and was acquitted at trial, according to Turkish news reports at the time.

“My father wouldn’t save me from prison if I killed someone in traffic,” joked Mr. Goktas, who has been performing since 2023 but whose last show garnered wide attention last month after he shared it online.

On Thursday, Mr. Goktas was detained at Istanbul Airport after returning to Turkey. A judge sent him to pretrial detention on accusations of insulting the president and instigating hatred in society by mocking religion.

Turkey’s government has also blocked access to websites that were critical of NATO and the summit, according to Engelli Web, a monitoring group. A number of Turkish journalists, including many who had covered previous NATO summits in other countries, said they had been denied accreditation for this one.

In a statement, a NATO spokesperson said the alliance “relies on the host nation to provide assessments on journalists from their country to ensure access to the meeting site.”

And last week, a cruise planner that had organized a trip oriented toward gay men was told its ship would not be allowed to dock in Turkey, Rich Campbell, the chief executive of Atlantis, the organizer, said in an interview. (Patti LuPone, who was scheduled to perform on the cruise, said on social media that she was “furious.”)

Turkey does not criminalize homosexuality, but Mr. Erdogan’s government has taken an increasingly hard line on L.G.B.T.Q. issues, including banning Pride parades.

The governor of Turkey’s Aydin Province said in a statement ahead of the cruise’s start that it had been organized by “groups known for behaviors that do not align with the structure of our society and our moral values,” and that it was “absolutely out of the question” for the ship to dock in the province.

A stop in Istanbul was also canceled, Mr. Campbell said. The Istanbul governor’s office also shut down an Istanbul gay bar that had invited the passengers to visit, citing unspecified “practices against regulations.”

Mr. Campbell said that his company had brought similar cruises to Turkey 13 times before without issue.

“Our guests are there for the same reason as any other tourist,” he said. “We’re not there in a gay pride rally or march or for political reasons ever.”

NATO is, at its core, a military alliance, whose members increasingly recognize the role that Turkey could play in its future, as concerns grow over the war in Ukraine and President Trump’s threats to reduce the U.S. role in the organization, or withdraw from it altogether.

Advocacy groups say that Turkey’s newfound importance to NATO has led member states to remain silent as Mr. Erdogan pursues a path toward greater autocracy.

“Turkey is so much more offside than any other NATO state with respect to democracy and human rights, and that should be a glaring difference for other countries,” said Emma Sinclair-Webb, the Turkey director for Human Rights Watch. “NATO member state leaders should look over the wall of the palace and see what is going on in the country.”

The two-day summit in Ankara, the capital, is expected to address the defense budgets and military industrial capacity of NATO countries. Governance inside member states is not on the meeting’s agenda and is unlikely to be discussed publicly, although the preamble of the alliance’s founding treaty says that its members are dedicated to the “principles of democracy, individual liberty and the rule of law.”

The Turkish government has repeatedly said that its legal system is free from political interference, and Mr. Erdogan has said that his political opponents are to blame for their legal troubles.

The Turkish authorities did not cite the NATO summit in connection with the wave of arrests, although some of them appeared to be aimed at preventing disturbances during the event.

The Ankara prosecutor’s office said last month that the police had detained 225 people and that 103 of them had been sent to pretrial detention during a security operation “to expose the activities of terror organizations around the country.”

Those detained included members of leftist groups that have staged protests in the past. They also included over a dozen environmental activists, an associate professor of political science at Ankara University, the editor of an L.G.B.T.Q. magazine and Deniz Goktas, a 32-year-old comedian.

Mr. Goktas’s routines have taken an edgy approach to politics and religion in Turkey, an overwhelmingly Muslim country with a constitutionally secular government. In one gag, he muses about Mr. Erdogan possibly going to therapy, saying that the president had gone from being a “shy dictator” to a “more-at-peace-with-himself dictator.”

In another, he refers to an episode in 1998, when Mr. Erdogan was the mayor of Istanbul. A woman died after Mr. Erdogan’s elder son, Burak, hit her with his car. Burak Erdogan told prosecutors that he was not at fault and was acquitted at trial, according to Turkish news reports at the time.

“My father wouldn’t save me from prison if I killed someone in traffic,” joked Mr. Goktas, who has been performing since 2023 but whose last show garnered wide attention last month after he shared it online.

On Thursday, Mr. Goktas was detained at Istanbul Airport after returning to Turkey. A judge sent him to pretrial detention on accusations of insulting the president and instigating hatred in society by mocking religion.

Turkey’s government has also blocked access to websites that were critical of NATO and the summit, according to Engelli Web, a monitoring group. A number of Turkish journalists, including many who had covered previous NATO summits in other countries, said they had been denied accreditation for this one.

In a statement, a NATO spokesperson said the alliance “relies on the host nation to provide assessments on journalists from their country to ensure access to the meeting site.”

And last week, a cruise planner that had organized a trip oriented toward gay men was told its ship would not be allowed to dock in Turkey, Rich Campbell, the chief executive of Atlantis, the organizer, said in an interview. (Patti LuPone, who was scheduled to perform on the cruise, said on social media that she was “furious.”)

Turkey does not criminalize homosexuality, but Mr. Erdogan’s government has taken an increasingly hard line on L.G.B.T.Q. issues, including banning Pride parades.

The governor of Turkey’s Aydin Province said in a statement ahead of the cruise’s start that it had been organized by “groups known for behaviors that do not align with the structure of our society and our moral values,” and that it was “absolutely out of the question” for the ship to dock in the province.

A stop in Istanbul was also canceled, Mr. Campbell said. The Istanbul governor’s office also shut down an Istanbul gay bar that had invited the passengers to visit, citing unspecified “practices against regulations.”

Mr. Campbell said that his company had brought similar cruises to Turkey 13 times before without issue.

“Our guests are there for the same reason as any other tourist,” he said. “We’re not there in a gay pride rally or march or for political reasons ever.”