Sudan ? Chances are slim that all the aid groups expelled by the Sudanese government will return, and alternative ways must immediately be found to help the millions of people in Darfur, President Barack Obama’s new envoy to Sudan said Saturday.

Envoy J. Scott Gration made his comments after touring Darfur’s fastest-growing refugee camp — one month after an international court issued an arrest warrant for Sudan’s president for war crimes in the vast, western region. In response, President Omar al-Bashir expelled 13 major international aid agencies — most of them operating in Darfur — and accused them of cooperating with the International Criminal Court.

Gration, a retired Air Force general, said the needs of more than 70,000 refugees in the Zamzam camp are barely being met largely because of Sudan’s expulsion of the aid groups. He warned that water could run out there in two months.