The Taiwan Ministry of Defense let the world know that numerous Chinese aircraft entered its air defense zone on Thursday.

Taiwan said it broadcast warnings and dispatched air patrol forces to deter the Chinese.

The incident occurred on the same day Russia invaded Ukraine. There are fears China could launch a similar attack in Taiwan, which it believes is part of the country.

Despite the timing of Thursday's events, a U.S. Defense official said the move is not unusual.

"China has done this in the past," the official told Fox News. "A couple months ago, [they] had similar type of events regularly."

Taiwan increased alert levels amid the Russia-Ukraine conflict. In response, China said Taiwan is "not Ukraine," Reuters reported.