The White House is pushing Congress to pass legislation that would prevent cybersecurity threats in wake of the recent massive federal data breach in the U.S. government.

On Thursday, the U.S. Office of Personnel Management, or OPM, revealed that hackers compromised personal data on 4 million government employees in what was the largest cyber-attack in U.S. history. According to OPM, the breach included records on 750,000 Department of Defense civilian personnel. Also included in those files were names, addresses, family members, education, Social Security numbers, security clearances and medical records.

Following the announcement, the Obama administration urged the Republican-controlled Congress to pass new cyber security rules. 

"The fact is, we need the United States Congress to come out of the dark ages and come into the 21st century to make sure we have the kinds of defenses that are necessary to protect a modern computer system," said White House spokesman Josh Earnest on Friday, urging Congress to approved the stalled legislation, according to Yahoo News.

"Congress must take action," to speed notifications on breaches and increase cooperation between the government and private companies, added Senate Intelligence Committee vice chairman Dianne Feinstein.

"It's impossible to overstate this threat," said the Democrat. "Trillions of dollars, the private data of every single American, even the security of critical infrastructure like our power grid, nuclear plants and drinking water are all at risk."

The U.S. government on Thursday admitted it suspects that the hackers behind the vast cyber-attack originated in China. However, analysts are questioning why the U.S. government waited so long to make it public.

In response, OPM spokesperson Samuel Schumach said that OPM decided to wait until June 4 to disclose the attack due to the diligence required before responding to an attack of this magnitude.

"With any such event, it takes time to conduct a thorough investigation, and identify the affected individuals," he told VOA.