SAN FRANCISCO (Reuters) – Facebook Inc on Wednesday said it would team with two U.S. non-profits to slow the global spread of misinformation that could influence elections, acknowledging that fake news sites were still read by millions.

The largest social network, under intense pressure to combat propaganda, said it would work abroad with the International Republican Institute and the National Democratic Institute, created in the 1980s and funded by the U.S. government to promote democratic processes. The institutes have informal ties to their namesake U.S. parties.

The partnerships, disclosed by company executives on a call with reporters, were among a slew of announcements from Facebook on election integrity ahead of major contests in Brazil next month and the United States in November.

As the company prepares a “war room” that will launch for Brazil’s vote, Facebook executives said that they had been testing the social network’s resilience with simulations of attempted manipulation such as election-eve efforts to suppress voting with false claims about ballot procedures.

Another training exercise looked at how the company would handle a burst of pages administered in other countries suddenly promoting material related to the U.S. election.

Even as Facebook ran exercises, an article published Wednesday by the Facebook-supported Digital Forensic Research Lab at the Atlantic Council found that of the four most popular articles being shared recently in Brazil about corruption, three were false.

“We know that there’s a lot more to do,” Facebook News Feed manager Greg Marra said when asked…