Beijing lashes out at any diplomatic action that might lend Taiwan legitimacy, and has responded with growing anger to visits by Western officials and politicians.
Taiwan's armed forces are well-equipped but dwarfed by China's. Tsai has been overseeing a modernisation programme and has made increasing defence spending a priority.
The foreign ministry in Beijing on Monday condemned the alleged hack, saying it "seriously endangers China's national security and users' personal data security".
The United States will continue to support a peaceful resolution of cross-Strait issues, consistent with the wishes and best interests of the people on Taiwan.
Ukraine had initially feared an IAEA visit at Zaporizhzhia would legitimise the Russian occupation of the site, before finally supporting the idea of a mission.