A hacker group calling itself the Syrian Electronic Army has attacked an American news organisation's website - but is refusing to say exactly why.
The group, which is said to support Syrian President Bashar al-Assad, targeted NPR's website and various Twitter accounts.
The new attacks follow similar assaults by the group against the BBC, Human Rights Watch and other groups who have published reports on the Syrian crisis.
They announced the hack on Twitter:
In response to a question about why NPR was targeted the group said "You can ask [NPR reporter] @deborahamos".
Deborah Amos has reported extensively about Syria and the crisis there since the uprising first began in March 2011. She was among the reporters praised for her "detailed reportage, often from dangerous locations" when NPR won a Peabody award for its coverage of the civil war.
NPR issued a statement and said it had corrected the stories that were vandalised.
"Late Monday evening, several stories on the NPR website were defaced with headlines and text that said 'Syrian Electronic Army Was Here.' Some of these stories were distributed to and appeared on NPR Member Station websites.
We have made the necessary corrections to those stories on NPR.org and are continuing to work with our Member Stations. Similar statements were posted on several NPR Twitter accounts. Those Twitter accounts have been addressed. We are closely monitoring the situation"