In a statement posted to the Pastebin website, Ghost Shell said the attacks were part of its #ProjectWhiteFox campaign to promote freedom of information online.
Images posted to the Pastebin page suggest the hacking group accessed some sites by attacking the databases many companies use to catalogue and curate website content.
Appealing to patriotic feeling, Mr Putin pointed out that Russia had no worthy monument to its dead of World War I, an event largely eclipsed by the October Revolution of 1917.
His return to office has been accompanied by a crackdown on dissent with the arrest of opposition activists and introduction of restrictive legislation.
He said that programmes to address Russia's long-term population decline were now working and in the past five months, the population had begun to grow naturally, with births exceeding deaths.
The DPJ promised more welfare spending and a better social safety net, but struggled to deliver amid the economic downturn and 11 March 2011 earthquake and tsunami.
He and his party say nuclear energy has a role to play in resource-poor Japan's future. Mr Abe has also called for a tough stance on the territorial row with China over East China Sea islands that both countries claim.
The gunman killed his mother at the home they shared before driving to the school in her car and opening fire. Reports say the guns used in the attacks were registered to her.
