Taiwan spotted two Russian warships off its eastern coast on Tuesday and sent its own aircraft and ships to keep watch, the island's defence ministry said.
In a statement late on Tuesday, the ministry said the two frigates sailed in a northerly direction off Taiwan's east coast and then "departed from our response zone" in a southeasterly direction off the port city of Suao, which is home to a major Taiwanese naval base.
Taiwan's military sent aircraft and ships to keep watch and activated shore-based missile systems, it added, without providing further details.
Russia's Interfax news agency reported on Tuesday that a detachment of ships of the Russian Pacific Fleet had entered the southern parts of the Philippine Sea to perform tasks as part of a long-range sea passage.
Taiwan has joined the United States and its allies in enacting wide-ranging sanctions against Russia following its invasion of Ukraine.
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