The FBI was aware of Russia likely being behind the breach on Democratic National Committee (DNC) but did not disclose this when it first warned DNC of hacking activities last fall, according to a Reuters report.

The report, quoting people familiar with the matter, also said that as a result, the DNC did not realize how serious the intrusions were till as late as March.

Sources told Reuters that the lack of full disclosure would have made DNC officials take proactive steps but, instead, hackers continued to have access to their servers for month, especially during a crucial period in the US polls.

However, an unnamed official quoted in the report defended the intelligence agency’s move saying it was acting in the interest of national security. “There is a fine line between warning people or companies or even other government agencies that they’re being hacked – especially if the intrusions are ongoing – and protecting intelligence operations that concern national security,” the official told Reuters.

Cybersecurity personnel and US officials have alleged that the Russian government was behind all the hacking activities on DNC, DCCC and the Clinton campaign but there is no official confirmation of this from the US government.

Read full report on Reuters.