With their history of xenophobia, no one expected Myanmar's generals to welcome with open arms an uninvited flotilla of U.S. warships trying to help bring relief to millions severely affected by Cyclone Nargis. But on Wednesday, the situation grew even bleaker as state-run media said the ships - a major force in relief efforts after the 2004 tsunami - would not be allowed in, appearing to dash what few hopes remained of the helicopter-equipped flotilla joining the relief operation. Instead, Myanmar gave a go-ahead for a far smaller operation of 10 helicopters from the UN's World Food Program - which must be chartered, flown in on cargo planes and reassembled in Bangkok. "The strings attached to the relief supplies carried by warships and military helicopters are not acceptable to the Myanmar people," said the New Light of Myanmar newspaper, a mouthpiece for the ruling junta. The announcement did not say exactly what strings were attached, and US military officials have repeatedly said that there were none. "This is purely a humanitarian mission," said Lt. Col. Douglas Powell, a spokesman for the stalled Operation Caring Response. "We have no ulterior motive other than to assist the Burmese people."