BEIJING - China's National Day military parade held no big surprises but there were tantalizing clues for experts assessing the modernization of the world's biggest fighting force.

Many focused on the Dongfeng 21C missile, which could force U.S. aircraft carriers to keep a greater distance if it is successfully developed into an anti-ship ballistic missile (ASBM). That would make it harder for the United States to come to Taiwan's aid in the event of a conflict.

The parade is a clear signal to Taiwan. The variety and quality of new arms on display has to be intimidating to Taiwan military officials, Wendell Minnick, Asia bureau chief for Defense News, said from Taipei.

China is basically saying to Taiwan independence advocates, 'forget it, you're going to lose'.

China views self-ruled Taiwan as a breakaway republic, to be retaken by force if necessary, although currently warming ties make an armed conflict less likely.

This missile is not completely developed yet but what we saw in the parade gives us a pretty good indication that they are reaching that capability, said Matthew Durnin, a Beijing-based researcher with the World Security Institute, adding that China still faces challenges in developing the integrated systems and satellites needed to properly guide an ASBM.

Beijing is modernizing the military to rely more on advanced technology and less on the sheer manpower of its 2.3 million soldiers. But its increased defense spending has raised fears, especially in Washington and Tokyo, about a lack of transparency.

From the standpoint of a mutually beneficial strategic (relationship) and greater transparency in military spending ... China should have a system so that ties can be friendly and peaceful, Japanese Chief Cabinet Secretary Hirofumi Hirano told a news conference in Tokyo.

Fighters, bombers and helicopters flew over central Beijing during the parade to the delight of citizens and also the national leaders on the podium.

China's aerospace industry, especially the fighters and bombers, has progressed slowly but still continues to be a bit of a weak point for China, Durnin said.

While parts of (the newest fighters) may have been developed in China they are still very dependent on Russian technology.

Washington may instead see a threat in the Dongfeng 31 intercontinental ballistic missile, or ICBM, which can be trucked around and is harder to target than silo-based missiles.

It's definitely a demonstration of strength for the Americans and Taiwanese, Minnick said of the parade.

But there were also clues in what wasn't shown.

Some strategists had expected that China might display a submarine-launched, nuclear-capable ballistic missile, or a new, highest-range land-based ICBM known as the Dongfeng 41.

So I think that probably says we know these programmes are in development, we know they are close to fruition, they just probably weren't quite to the stage that China was comfortable or motivated to show them in the parade, Durnin said.

(Additional reporting by Ralph Jennings in Taipei and Chisa Fujioka in Tokyo)