Defense Secretary Chuck Hagel has ordered all military personnel returning from Ebola response missions in West Africa to be held in a 21-day quarantine.

Hagel signed the order Wednesday morning, accepting a recommendation from the Joint Chiefs of Staff. The Army days earlier had imposed such a policy on its own servicemembers, but the new order applies to all branches.

"The fact is the military will have more Americans in Liberia than any other department," Hagel said, explaining his decision at Wednesday's "Washington Ideas Forum." He also said military families had discussed the idea, and "very much wanted a safety valve on this."

The decision by Hagel further drives the divisions among the White House -- which has downplayed the need for mandatory quarantines -- and a range of other policymakers, particularly at the state level.

California, the latest state to enact a tighter policy than the federal government, on Wednesday announced a 21-day quarantine for travelers from the hot-zone in West Africa who came in contact with infected individuals.

In Maine, the returning nurse who battled New Jersey Gov. Chris Christie over her mandatory quarantine also is now battling her home state after returning to Maine.

Maine health officials are in the process of filing a court order to force Kaci Hickox to comply with the state's "voluntary" 21-day quarantine period for health care workers who treated Ebola patients. Hickox, on Wednesday, told NBC's "Today" that she doesn't "plan on sticking to the guidelines" and is "appalled" by the home quarantine policies "forced" on her.

"I truly believe this policy is not scientifically nor constitutionally just, and so I'm not going to sit around and be bullied around by politicians and be forced to stay in my home when I am not a risk to the American public," she said, saying she's in "perfectly good health."

President Obama and his top health advisers also have played down the need for blanket quarantine policies for health care workers. The White House, though, has left open the door for the Pentagon to impose its own policies, arguing that the military and health workers are two entirely separate issues.

Hagel noted, for instance, that many of those in the military are not "volunteers" for the Ebola mission.

Pentagon spokesman Col. Steve Warren said the number of troops quarantined at a base in Italy is now at 42, up from 11 a day earlier.

A statement issued from the Pentagon said all returning servicemembers would be subjected to a 21-day "controlled monitoring," which is effectively a quarantine.

Hagel ordered the Joint Chiefs to develop a detailed implementation plan for review within 15 days.

He also wants the Joint Chiefs to conduct a review of the new policies within 45 days -- from there, they'll determine whether to continue the quarantines.