HONG KONG — China is spending billions of dollars on a major push to make its own microchips, an effort that could bolster its military capabilities as well as its homegrown technology industry.

Those ambitions are starting to be noticed in Washington.

Worries over China’s chip ambitions were the main reason that United States officials blocked the proposed purchase for as much as $2.9 billion of a controlling stake in a unit of the Dutch electronics company Philips by Chinese investors, according to one expert and a second person involved with the deal discussions.

The rare blockage underscores growing concern in Washington about Chinese efforts to acquire the know-how to make the semiconductors that work as the brains of all kinds of sophisticated electronics, including military applications like missile systems.

In the case of the Philips deal, the company said late last month that it would terminate a March 2015 agreement to sell a majority stake in its auto and light-emitting diode components business known as Lumileds to a group that included the Chinese investors GO Scale Capital and GSR Ventures. It cited concerns raised by the Committee on Foreign Investment in the United States, which reviews whether foreign investments in the country present a national security risk.