Beijing ? Robert Gates, making his first visit to China as defense secretary, is expected to press the Chinese to do more to prevent Iran from acquiring nuclear capabilities.

Before he left Saturday for the trip, Gates made it clear that he is pursuing a closer alliance with China, and said he doesn’t see the communist giant as a military threat.

But at the same time, senior defense officials said the Pentagon is still frustrated by China’s failure to be more open about its military ambitions. And Gates will probably push China to better explain its anti-satellite test early this year.

In January, a Chinese missile shattered a defunct Chinese weather satellite, drawing immediate criticism from the U.S. and other countries, who questioned China’s commitment to peaceful development in space. Since then, U.S. officials have struggled to get better answers from the Chinese about it.