SAN FRANCISCO (AP) -- Google Inc. countersued Microsoft Corp. Thursday in a legal battle over a prized research engineer that illustrates the escalating tensions between the technology titans. The tussle began earlier this week after Google -- the maker of the Internet's most widely used search engine -- raided Microsoft's management ranks by hiring Kai Fu-Lee to open a new research and development office in China. Redmond, Wash.-based Microsoft, the world's largest software maker, promptly sued Google and Lee in Washington state court, alleging a noncompete agreement that the engineer signed in 2000 prevented him from defecting. Google retaliated...