Shortly after setting foot in the United States, Kenneth Bae said he was grateful to the U.S. government for securing his release and revealing that his time there offered lessons, according to Reuters.

Bae and Matthew Miller, another American who had been held captive in North Korea, arrived back in the U.S. on Saturday night at a Washington State military base after a top U.S. intelligence official secured their releases, Reuters reported. Miller is from Bakersfield, California, and Bae is from Lynnwood, Washington.

"It's been an amazing two years, I learned a lot, I grew a lot, I lost a lot of weight," said Bae, who is a Korean-American missionary, according to NBC News. "I just want to say thank you all for supporting me and standing by me."

Bae had been sent to a hospital before being released, and was in better shape when he arrived than his family expected.

A senior Obama administration official said the president approved the mission last week, and U.S. officials spent the next several days planning the trip, Reuters reported.

Bae was serving a 15-year sentence for alleged anti-government activities, and was detained in 2012 while leading a tour group to a North Korean economic zone, according to NBC.

North Korea said Miller, who was serving a six-year jail term, was guilty on charges of espionage after he allegedly ripped up his tourist visa at Pyongyang's airport in April and demanded asylum, Reuters reported.

Miller wanted to experience prison life so he could secretly investigate the country's human rights situation.

Bae and Miller were the last two Americans held captive by the reclusive Communist country, according to Reuters. Last month, North Korea released Jeffrey Fowle of Miamisburg, Ohio, who was held for nearly six months after leaving a Bible in a nightclub with hopes that it would reach North Korea's underground Christian community.