Former AG Eric Holder sends mysterious 3 a.m. tweet telling DOJ staff to 'be prepared, be strong'

Eric Holder, who served as attorney general under former President Barack Obama, posted an eyebrow-raising tweet early on Friday morning in which he told career officials at the FBI and Department of Justice to "be prepared" and "be strong."

"To the career men & women at DOJ/FBI: your actions and integrity will be unfairly questioned," Holder wrote. "Be prepared, be strong. Duty. Honor. Country."

Holder didn't post any followup tweet after this, and would not say if he had any inside information about something that was about to happen at the DOJ or FBI.

Holder posts fairly infrequently on Twitter, and many of his previous tweets have involved his opposition to Republican efforts to repeal the Affordable Care Act, as well as fighting "racial gerrymandering" across the country.