Li Deyu
Chen was himself soon involved in a policy argument against Li Deyu, as Tang's long-time ally and vassal Huigu had recently been defeated by Xiajiasi, and Huigu remnants were approaching Tang borders. One major group of Huigu remnants, led by the noble Wamosi, approached the Tang city of Tiande (天德, in modern Bayan Nur, Inner Mongolia) and sought food aid, offering to submit to Tang. The defender of Tiande, Tian Mou (), suggested that Wamosi's offer be rejected and that Tang forces attack him, along with allied Tuyuhun, Shatuo, and Dangxiang tribes. Li Deyu opined differently, believing that Wamosi's offer should be accepted and that food should be supplied to the Huigu remnants. Chen opposed Li Deyu, arguing that in effect, it would be aiding the enemy. Emperor Wuzong eventually agreed with Li Deyu.