Taiwan’s Defense Ministry is urging Chunghwa Telecom, the the island’s largest telecom company, to improve its cybersecurity following a data breach that compromised government-related information.

The hackers, reportedly believed to be backed by the Chinese government, made off with 1.7TB of data following the Chunghwa compromise and have put it all up for sale on the Dark Web.

The Defense Ministry confirmed the breach to news service AFP on March 1.

“The initial analysis of this case is that hackers obtained Chunghwa Telecom’s sensitive information and sold it on the dark web, including documents from the armed forces, foreign affairs ministry, coast guard and other units,” Taiwanese officials said in a statement. The Defense Ministry added that no confidential information was leaked.

“We have asked the contractor involved to strengthen its information security control to prevent any further incidents,” the statement said.