On 29 December 2023, he was appointed as the 14th Minister of National Defense; he succeeded Li Shangfu who was removed from office in October 2023.

[9] According to political scientist Wen-Ti Sung, the selection of Dong as the defense minister was possibly a sign of ongoing purges within the PLA Rocket Force and the Central Military Commission (CMC)'s Equipment Development Department.

[17] Prior to the defense ministers meeting, on April 26, he met with high-ranking Kazakhstani politicians including President of Kazakhstan Kassym-Jomart Tokayev.

[18] On 31 May 2024, Dong attended the 2024 Shangri-La Dialogue in Singapore where he met with United States Secretary of Defense Lloyd Austin.

"[21] On 20 November 2024, Dong held high-level talks with his Indian counterpart Rajnath Singh on the sidelines of 11th ASEAN Defence Ministers’ Meeting-Plus at Vientiane, Laos.

The meeting between the two defence ministers came after the Indian and Chinese militaries completed disengagement of troops at friction points at the Line of Actual Control between the two countries.

"[22] In late November 2024, former and current U.S. officials who spoke to the Financial Times stated that Dong was under investigation due to suspicion of corruption.