US President Donald Trump blamed his predecessor, Barack Obama, on Saturday for not taking action to prevent the alleged Russian hacking attack into the computer networks of Hillary Clinton’s campaign and the Democratic National Committee (DNC) during the 2016 presidential election.

On Friday, a Grand Jury indicted 12 Russian intelligence officers for participating in efforts to infiltrate those computer networks to obtain damaging information about Clinton and the DNC, which was then dumped online, Efe reported.

“The stories you heard about the 12 Russians yesterday took place during the Obama Administration, not the Trump Administration,” Trump said on Twitter.

This is the first time that the president has commented on the indictments presented Friday by Robert Mueller, the special counsel who is investigating whether the Trump campaign colluded with the Kremlin.

READ | Summit between Donald Trump and Vladimir Putin should proceed: Mike Pompeo

“Why didn’t they do something about it, especially when it was reported that President Obama was informed by the FBI in September, before the Election?” Trump said.

Those accused of the Russian hacking attack allegedly spread computer viruses through the email accounts of DNC and Clinton campaign staffers and volunteers, obtaining passwords that allowed them to access information.

The hackers then reportedly posed as US activists and used Facebook and Twitter to spread the information they obtained.

The Russian government has repeatedly denied that it had any role in the DNC and Clinton campaign hacking.

Trump will meet with Russian President Vladimir Putin for a bilateral summit on July 16 in Helsinki, in which the two leaders are expected to discuss the conflicts in Syria and Ukraine, arms control, and Russia’s suspected meddling in the 2016 US election.