This study examines the perceptions and responses of Vietnamese teachers of English as a Foreign Language (EFL) to academic integrity concerns that arise from the use of AI, specifically chatbots like ChatGPT, in foreign language education. The study employed an open-ended survey to collect data from 31 Vietnamese EFL teachers who were asked to share their views on AI-based academic dishonesty, identify perceived causes, outline consequences for students engaging in AI-based plagiarism, and articulate their pedagogical responses to the issue. The study found that teachers primarily attributed students' AI-driven plagiarism to a deficiency in original ideas, poor learning attitudes and motivation, and students' linguistic competencies. The over-reliance on AI was identified as a hindrance to the development of knowledge and skills such as critical thinking and language proficiency. In response to academic dishonesty, teachers advocated for increased regulations, the implementation of AI-based plagiarism detectors, and education on responsible AI use. The findings underscore the importance of adapting language teaching pedagogies and assessments to incorporate personalised learning and process-oriented teaching approaches that support critical thinking and genuine learning motivation. The insights derived from this research contribute to a deeper understanding of EFL educators' perspectives, offering valuable input for the development of policies and practices aimed at promoting academic integrity in the AI era. [Note: The page range (28-47) shown on the PDF is incorrect. The correct page range is 28-48.]