Taiwan's Ministry of Defense announced on Tuesday that China had launched a satellite and issued a warning urging vigilance days before the island's elections.
Taiwan will hold presidential and parliamentary elections on Saturday in what China describes as a choice between war and peace.
A presidential alert sent to residents' cellphones was in English, warning of a missile passing at high altitude.
The alarm sounded during an international press conference by Taiwanese Foreign Minister Joseph Wu.
He clarified that it was a satellite launch, told reporters there was no need to worry, and continued with the press conference.
China considers Taiwan, about 160 miles off its east coast, a rebel province that should be brought under its control.
