The Obama administration is seeking China’s help in stopping North Korea from launching future cyber-attacks, the New York Times reports.

President Barack Obama said on Friday that the U.S. would retaliate for the attack on Sony Pictures, which the FBI linked to North Korea earlier in the day. He said the U.S. will levy a “proportional response” that would come “in a place and manner and time that we choose,” but didn’t divulge details.

“What we are looking for is a blocking action, something that would cripple their efforts to carry out attacks,” an official told the New York Times.

The Chinese have reportedly not responded yet, but their cooperation could be paramount, as virtually all of North Korea’s telecommunications use Chinese-operated networks. The Sony cyber-attacks appear to have been routed through China and then conducted through servers in Singapore, Thailand and Bolivia. Officials said the countries have been been asked to cut off access for the hackers.

Approaching China is the first part of the administration’s plan of action following the first major, state-sponsored cyber-attack on a company in U.S. history. However, the U.S. also fears escalating matters with North Korea, another official told the New York Times.

“There are a lot of constraints on us, because we live in a giant glass house,” the official said.

The FBI announced on Friday that North Korea was “responsible” for the hack, which led the studio to cancel its Christmas Day release of “The Interview.” The country denied responsibility on Saturday, instead proposing a joint investigation into the hacking attack.

“The U.S. should bear in mind that it will face serious consequences in case it rejects our proposal for joint investigation,” an unidentified North Korean Foreign Ministry spokesman warned.