Basically in his role as chairman of the Joint Chiefs of Staff (a council of the different military branches) he called his Chinese counterpart during the election chaos to assure them Trump couldn't unilaterally declare war on China:
Woodward and Costa describe how Milley learned in October 2020 that the Chinese had become concerned that Trump would preemptively attack China because Trump was losing the 2020 election and his rhetoric against China was growing increasingly hostile.
Milley again called his Chinese counterpart on Jan. 8, 2021, two days after the attack on the U.S. Capitol, to again reassure him that the American government was stable and not an immediate threat to China.
Please don't ask me for a source because I don't have one, but I distinctly remember reporting about Pence being warned not to trust any unfamiliar secret service agents, and refusing to get into a car after the riot began because he did not recognise the driver.
Edit: Found a source: