Mr. Drummond said that an attack originating in China was aimed at its corporate infrastructure.
While the full scope of the attacks on Google and several dozen other companies remains unclear, the events set off immediate alarms in Washington, where the Obama administration has previously expressed concern about international computer security and attacks on Western companies.
Neither the sequence of events leading to Google’s decision nor the company’s ultimate goal in rebuking China is fully understood. But this was not the first time that the company had considered withdrawing from China, according to a former company executive. It had clashed repeatedly with Chinese officials over censorship demands, the executive said.
Google said on Tuesday that that in its investigation of the attacks on corporations, it found that the Gmail accounts of Chinese and Tibetan activists, like Ms. Seldon, had been compromised in separate attacks involving phishing and spyware.
Independent security researchers said that at least 34 corporations had been targets of the attacks originating in China.