The ROC also 'vows reunification' with the Chinese mainland. It's a standard line in the One China diplomatic framework which both states follow.
Edit: can we get the title changed to "Xi vows 'peaceful reunification' with Taiwan"? This better reflects the content of the article:
BEIJING, Oct 9 (Reuters) - Chinese President Xi Jinping vowed on Saturday to achieve "peaceful reunification" with Taiwan, and did not directly mention the use of force after a week of tensions with the Chinese-claimed island that sparked international concern.