[Just a few years ago on a visit to Germany] Turkish Prime Minister Recep Tayyip Erdogan described demands that Turks in Germany "assimilate" as a crime against humanity.
Here is a video expose of the largest Islamic organization in Germany Millî Görüş (IGMG), strongly influenced by the former Turkish President, also said to be the country's first Islamist president, the group had been under criminal investigation in May 2010. They created a video game for children where they must fight against the enemy democracy [@ 5:13 mins].
German President Christian Wulff has urged the three million Turks living in Germany to learn German better in order to integrate better.
He was addressing the Turkish parliament just days after Chancellor Angela Merkel said multiculturalism in Germany had been a failure.
He stressed integration did not mean giving up Turkish culture and identity.
A BBC correspondent says many Turks suspect Berlin of seeking to whip up anti-immigrant sentiment.
Earlier this month, Mr Wulff sought to assure his country's Muslims, most of whom are Turks, that "Islam belongs to Germany".
President Wulff is a more emollient speaker than Chancellor Merkel and he was careful to put his points diplomatically to his Turkish hosts but his message about needing to integrate was the same as Mrs Merkel's, the BBC's Jonathan Head reports from from Istanbul.
'Duty for all'
"Immigrants have made Germany more plural, more open and more worldly," Mr Wulff said in Ankara.
"But living in a plural society is also a huge challenge.
"Turkey 'can' show that Islam and democracy, Islam and the rule of law, and Islam and pluralism needn't be contradictory."
Mr Wulff also urged Turkey to give Christians equal rights to exercise religious freedom and train their own priests.
"Christianity belongs to Turkey," he said.
Turkish President Abdullah Gul thanked Mr Wulff, when they met earlier on Tuesday, for supporting Germany's Muslims.
"It is a duty for all of us to ensure every citizen speaks the language of the country they reside in fluently," Mr Gul said.
"The use of integration issues for political capital should be avoided, everybody must contribute to a solution instead," he added.
President Wulff also asked for the co-operation of Turkey's powerful Religious Affairs Department, which trains and dispatches imams to minister to the Turkish community in Germany for four-year stints.
The German authorities believe the imams could play an important role in helping Turks to integrate if they were more rooted in Germany - they would like imams to be trained locally instead.
There is a better understanding between the two countries on this issue than a few years ago, our correspondent adds.
On that occasion, Turkish Prime Minister Recep Tayyip Erdogan described demands that Turks in Germany "assimilate" as a crime against humanity.