The White House has also yet to vow a “proportional” response, as it did following the bruising cyberattack on Sony Pictures Entertainment, which it blamed on North Korea.

In the Sony case, “proportional” meant a new round of economic sanctions on the reclusive East Asian nation.

Since then, President Obama has signed an executive order giving the Treasury Department more clout to impose similar sanctions on any foreign regime caught hacking the U.S.

But experts are wary the administration will make the OPM hack its inaugural test case for this new tool.

“I don’t know that frankly, in this case, in the absence of any independent evidence that doesn’t rely on [classified] intelligence sources, that it would make sense to do that,” said Chris Finan, a former Obama administration cybersecurity adviser. “What do you get in return?”

Finan and others believe such sanctions would simply provoke China and do little to change its hacking behavior.