German Foreign Minister Joschka Fischer has said Turkish entry to the European Union would be as important for Europe as the D-Day invasion 60 years ago.
Joschka Fischer said Turkey was "heavyweight"
Mr Fischer told the BBC that Europe needs to bring in Turkey and use its influence to make the country secular.
Turkish membership was a key way to liberate Europe from the threat of insecurity from the Middle East and "terrorist ideas", the minister added.
There is significant public opposition to Turkey's accession in Germany.
But Mr Fischer indicated the state's entry would be strategic in the long-term.
"To modernise an Islamic country based on the shared values of Europe would be almost a D-Day for Europe in the war against terror," he said.
"It would be the greatest positive challenge for these totalitarian and terrorist ideas."
The new European Commission has recommended that Turkey is now ready to begin full negotiations on joining the EU.
At a summit in December, the EU leaders will use the report as the basis for deciding whether or not to open negotiations on the Turkish bid.
"Turkey is heavyweight and will be the biggest country in the future," the minister told Radio 4's Today programme.
Turkey - a bridge between East and West?
"The big question will be is Europe ready to digest such a big member state?"
Mr Fischer said that before the 11 September 2001 attacks he had been sceptical about the EU bordering Syria, Iraq and Iran.
He suggested it was now strategically important.
"Our security will be defined for at least five decades in this region... whether we like it or not."
Germany has been more forthright in its views on the EU's relationship with Turkey than France, which is deeply divided on the issue and has promised a referendum.
In the wide-ranging interview, the minister also said that his country supports efforts to re-build Iraq, but will not send troops to the country.
Mr Fischer also described the UN as "indispensable", but urged reform.
"It is weak and we must reform that," he said.