The statement e-mailed to journalists and posted on a Web site used by the Taliban said more foreign troops are dying because Taliban fighters have learned NATO tactics and are able to shoot down more aircraft, the Los Angeles Times reported.
"All of these give us good news of an imminent victory and a bright future," the message said.
It was signed by Mullah Mohammad Omar, the reclusive one-eyed leader of the Afghan Taliban, and released Monday on the eve of one of Islam's most important holidays that marks the end of Ramadan.
Daniel Markey, a Washington-based fellow with the Council on Foreign Relations, said the aim of the message was to characterize the Taliban struggle as a defense against invaders.
"Omar certainly seems to be continuing an earlier effort to soften the [Taliban] image among Afghans," said Thomas Ruttig, co-director of the Kabul-based Afghanistan Analysts network.