China's unveiling of "carrier-killer" missiles and cuts in troop numbers on Thursday underlined its shift towards naval strength amid growing Pacific rivalry with the US, analysts said.

More than a dozen anti-ship ballistic missiles capable of travelling at 10 times the speed of sound were shown at a massive military parade in Beijing, with state television calling them a "trump card" in potential conflicts and "one of China's key weapons in asymmetric warfare".

For a fraction of the cost of an aircraft carrier the missile threatens to alter the balance of power in the Pacific.

The land-based DF-21D intermediate-range missile is said to be equipped with onboard terminal guidance systems that give it the unprecedented ability to attack a moving target, such as a carrier group at sea.

For decades, the United States' fleet of aircraft carriers has been a key component of its ability to project power around the world, and Andrew Erickson of the Washington-based Jamestown Foundation has described the DF-21D as a "Frankenweapon" that is "potentially unpredictable and disruptive".

The missile "serve as a deterrent which requires rivals in the region to think twice about deploying aircraft carrier groups against China," James Char, an analyst at Singapore's Nanyang University told AFP.

The technology is untested but it underlines "the growing importance of China's naval forces" as Beijing seeks to project its power more widely in the air and on sea, he added.

Also on show in Beijing were longer-range weapons, prompting one commentator on Chinese state television to exclaim: "Look at this missile! It can hit Hawaii!"

China said in May that the People's Liberation Army (PLA) navy will put a greater emphasis on "open seas protection", rather than "offshore waters defence" alone.

At the same time its air force will shift focus "from territorial air defence to both defence and offence", it said.

Beijing is "very concerned with what its rivals, in particular the US naval forces, might do to it," Char added.

China has been boosting its military budget with double-digit percentage increases for decades, as it takes a more assertive stance in territorial disputes with Asian neighbours in the East and South China Seas.

But the US, which has dominated the Pacific since World War II, has pushed back with a "pivot" to Asia which Barack Obama has said is aimed at maintaining "American leadership" in the region.

Washington spends far more on its military than China, and is treaty-bound to defend Japan and South Korea, while other allies in the region include Taiwan and the Philippines.

"There's no doubt that it will be a game changer" if the DF-21D has its claimed capabilities, Jon Grevatt of IHS Jane's told AFP.

Arthur Ding, a military expert at Taiwan's National Chengchi University, cautioned that the missiles' effective use required advanced co-ordination between satellites and ships, and that the US has "many countermeasures" available.

But he added that it will "somewhat complicate US operations in this region".

- Firepower and mobility -

Immediately before the parade, President and army head Xi Jinping announced that the PLA -- currently the largest standing military in the world with 2.3 million troops -- would cut 300,000 staff.

China's troops would "carry out the noble mission of upholding world peace", he added, and would never "seek hegemony".

It is the latest in a series of giant cuts to the bloated PLA, which Beijing has reduced by around two million troops since the 1980s as it seeks to craft a more efficient fighting force.

The latest decline was "within expectations" and had been under discussion for several years, Taiwan-based analyst Ding said, adding: "Overall firepower and mobility has been much better improved, so the cuts can be done."

China's defence ministry said the cuts would "mainly target troops equipped with outdated armaments, administrative staff and non-combatant personnel" and would make the armed forces "slimmer and more capable".

Grevatt of IHS Janes said they would have a "long-term positive effect" on China's military capabilities.

"The strength of a military these days is not about the numbers of troops," he added.

The military has been one of the targets of Xi's much-publicised anti-corruption drive -- which analysts and diplomats say can be used for internal faction-fighting -- with two of China's most senior generals falling victim to it in the past year.

Corruption - especially bribery for promotions -- is thought to be endemic in China's army, but the parade provided a show of unity and adherence to the chain of command, troops and generals alike turning their eyes to Xi and saluting as they passed.

"The high ranking army officials are nervous because many of them probably were promoted because of bribes," Ding said.

"They have to show their loyalty. Xi has firm control of the military."