"Turkey occupies a key position in the coalition -- it is hosting aircraft and making other contributions," Carter told reporters in Paris, where he has been meeting defense ministers from several countries involved in the so-called anti-ISIL coalition.
Turkey has time and again been accused of supporting the ISIL terrorist group in Syria. Ankara has also come under fire for not doing enough to halt the advance of ISIL as well as for its perceived reluctance to crack down on militants using its territory to travel into Syria, gripped by deadly unrest since March 2011.
"I do believe that Turkey can do more, and therefore the kind of campaign plan I was discussing with other ministers... would very, very much benefit from a stronger effort by Turkey," Carter said, AFP reported.
He said the priority for Turkey, a NATO member, was gaining greater control over its "long and difficult border" with Iraq and Syria.
"The Turkish border is a place where ISIS fighters have gone back and forth, logistics and supplies for ISIS have been furnished," said Carter, using an alternative name for ISIL.