US President Donald Trump welcomed Turkish President Tayyip Erdogan to the White House and told reporters the two would have "long and hard discussions" that would make their bilateral relationship better.
"It's a great honour to have President Erdogan from Turkey here," Mr Trump said before the start of their meetings.
"We're going to have long and hard discussions. I know that they will be very successful. We've had a great relationship and we will make it even better.
So we're going to have a very, very strong and solid discussion."
Ministry staff arrested in coup probe in Turkey
Meanwhile, Turkey detained dozens of energy and education ministry staff in an investigation targeting the network of a US-based cleric the government accuses of orchestrating last July's attempted coup.
50,000 people have been formally arrested in court cases targeting supporters of cleric Fethullah Gulen.
President Erdogan is seeking Mr Gulen's extradition.
Arrest warrants were issued for 60 energy ministry-linked workers and 25 education ministry staff and 40 have already been detained, state-run Anadolu news agency reported.
Many of them had previously been dismissed from their posts.
Anadolu said the suspects were believed to have been users of Bylock, an encrypted messaging app the government says was used by Mr Gulen's followers.
The arrest warrants came after a court yesterday jailed opposition newspaper Cumhuriyet's online editor pending trial on a charge of spreading terrorist propaganda, the paper said.
Oguz Guven joined a dozen journalists from Cumhuriyet, long a pillar of the secularist establishment, who are already in jail facing sentences of up to 43 years in prison, accused of supporting Mr Gulen's network.
Mass detentions were initially supported by many Turks and authorities say the measures are justified by the gravity of last July's attempted coup, in which rogue troops commandeered warplanes to bomb parliament and used tanks to kill 240 people.
But criticism has mounted as the arrests widened, with relatives of many of those detained or sacked denying their involvement in the coup and calling them victims of a purge.
A total of 150,000 people, mainly civil servants, security personnel and academics, have been suspended or sacked as part of a related crackdown.
"I fear for the Turkish people as they enter this new stage of authoritarianism," Mr Gulen said in a Washington Post article published to coincide with Mr Erdogan's White House meeting.
He has denied any role in what he called the "deplorable coup attempt".
Mr Erdogan accuses Mr Gulen, a former ally of the Islamist-rooted ruling AK Party, of infiltrating Turkish institutions to establish a 'parallel state'.
In an article in Foreign Policy magazine calling for the cleric's extradition, Turkish Foreign Minister Mevlut Cavusoglu said Mr Gulen and his network represented a grave and imminent threat to Turkey's national security and constitutional order.