BEIJING – U.S. Defense Secretary Robert Gates says China’s rapidly developing defense capabilities are worrisome to the United States.

China has made strides in building a new stealth fighter jet and Washington is also concerned about a new ballistic missile that could theoretically explode a U.S. aircraft carrier nearly 2,000 miles out to sea. China has also apparently beaten U.S. estimates to develop that weapon.

Gates arrived Sunday in Beijing for talks about these weapons and other military issues with Chinese leaders.

“They clearly have potential to put some of our capabilities at risk,” Gates told reporters. “We have to pay attention to them, we have to respond appropriately with our own programs.”

The United States has long known that China wanted to field a stealth jet, but development outpaced U.S. intelligence estimates, Gates said.