Yangon, Myanmar (AP) -- U.N. Secretary-General Ban Ki-Moon is on the diplomatic mission of a lifetime. He hopes to persuade Myanmar's military regime to open its border to international relief efforts.

Ban arrived in Myanmar's capital early Thursday. Before he left Thailand, he told reporters that this is “a critical moment for Myanmar.”

By the Junta's own count, at least 134,000 people are dead or missing from Cyclone Nargis, which swept through the country's heartland nearly three weeks ago.

The U.N. says up to 2.5 million survivors are hungry and homeless and there are worries about disease outbreaks.

Ban is scheduled to meet with government ministers and international aid agencies. He's also to be flown by helicopter to the hard-hit delta area.