Meanwhile, as CNN reported on Sunday, the rescue effort in Thailand has assembled divers and Navy Seal personnel from various countries including the United States and Thailand itself, which saw one elite diver die on Friday during the operation to save the boys.
The soccer team's ordeal has drawn huge media attention in Thailand and overseas, as monsoon conditions worsened amid a frantic search to find the trapped youngsters.
But Narongsak said earlier that mild weather and falling water levels in recent days had created optimal conditions for an underwater evacuation. "If we wait and rain water comes in, our readiness will be lower than now", said Narongsak Osottanakorn, governor of Chiang Rai province.
Two ambulances were seen leaving the cave in northern Thailand hours after the operation began to rescue the trapped young soccer players. After the boys emerge from the cave, they will be taken in an ambulance to be evacuated from the cave site via helicopter, provided weather conditions are safe for flying. Each of the boys will be accompanied by two divers.
The rescue teams had rehearsed the plan for several days, Mr. Narongsak said, and had managed to drain the water level in the cave considerably, but needed to move fast.
It was expected that the boys would not have to dive to get out of the cave - as had been previously predicted - because the cave system would largely be walkable, according to officials. 'I know that we, the USA side, are prepared to stay as long as it takes to support the Thai operation.' She added that the core team consists of 17 people.
Residents of the nearby town of Mae Sai, located directly on the border with Myanmar around seven miles away from the cave entrance, have been following the saga of the boys' disappearance and rescue efforts intently.
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They were discovered by a team of British divers on Monday and rescue operations have been meticulously planned all week.
An Australian doctor who is part of the rescue mission checked the health of the boys on Saturday night and gave the all-clear for the operation to proceed.
David Strike has known Dr Harris for more than 10 years, and says his medical expertise and experience as a cave diver and retrieval expert is invaluable.
Last week, as hopes for rescue were fading, divers found that the boys and their coach had survived and were trapped on a ledge deep inside the cave. "We have tried all possible ways to get the boys out, but sometimes we can't win over nature".
The announcement of USA government involvement was sudden and this tweet is looked at as Trump's first public comment on the rescue mission.
AFPnews agency quotes an official saying four boys in Thai cave have reached a rescue camp, and will walk out of the cave soon.