The Islamic State group appeared to try to keep morale high among its supporters in a new audio message released on Saturday, which also called for attacks on the US during the holy month of Ramadan.
The audio recording reportedly featuring IS spokesman Abu Mohamed al-Adnani was posted online late Saturday evening after much fanfare by IS supporters on Twitter.
"Will we be defeated if we lose Mosul, or Sirte, or Raqa, or all the cities, and go back to how we were before?" Adnani said.
The three cities are IS's strongholds in Iraq, Libya, and Syria respectively.
"No. Defeat is only losing the desire and the will to fight," Adnani continued, in his first voiced speech since October.
The spokesman appeared to mock the United States, which is leading a coalition of countries in an air war against IS in Iraq and Syria, for failing to definitively defeat IS.
He said even "20,000 air strikes" by the coalition had not destroyed IS.
Adnani also called for attacks on the US and Europe during the holy month of Ramadan, which starts in early June this year, an appeal he made at the same time last year when urging supporters to seek "martyrdom".
On Friday, flyers apparently dropped by the coalition on Raqa city in northern Syria urged residents to leave the city, perhaps ahead of an offensive by anti-IS forces to recapture it.
"It would appear IS is more clearly acknowledging its limitations in holding territory" while stressing the "idea of living on despite losses," wrote jihadism expert Aymenn al-Tamimi in reaction to Adnani's recording.
IS has seized swathes of territory in Syria and Iraq to create a self-styled "caliphate." Its leader, Abu Bakr al-Baghdadi, has received pledges of alliance from jihadist groups around the world.