The United States' campaign to encourage China to be more open about its military growth and intentions got a symbolic boost Monday with a tour for Defense Secretary Chuck Hagel of the country's first aircraft carrier.

Hagel got a rare tour of China's first aircraft carrier, becoming the first foreign visitor to go aboard the ship, according to Chinese leaders.

US officials on Monday said the tour of China's aircraft carrier was a good first step.

"The secretary was very pleased with his visit today aboard the carrier Liaoning," said Pentagon press secretary Rear Adm. John Kirby. "He understands how significant it was for the (Chinese military) to grant his request for a tour, and he was impressed by the professionalism of the officers and crew. He hopes today's visit is a harbinger for other opportunities to improve our military-to-military dialogue and transparency."