(Reuters) – Top officials from Facebook Inc (FB.O), Alphabet Inc’s (GOOGL.O) Google and Twitter Inc (TWTR.N) appeared remotely before U.S. lawmakers on Thursday at a virtual hearing on foreign influence and election security.

The Silicon Valley leaders were testifying at a House of Representatives Intelligence Committee hearing about their actions taken to combat election interference since the 2016 U.S. elections, as the country moves toward the Nov. 3 presidential contest.

“As I look across the landscape I cannot say I am confident that the 2020 election will be free of interference by malicious actors, foreign or domestic,” said House Intelligence Chairman Adam Schiff at the hearing.

Ahead of the hearing, witnesses described each company’s work to combat disinformation and improve election integrity. The written opening statements were from Nathaniel Gleicher, Facebook’s head of security policy; Nick Pickles, director of global public policy strategy and development at Twitter, and Richard Salgado, director for law enforcement and information security at Google.

Twitter’s Pickles stressed that the problem went beyond content moderation.

“Removal of content alone will not address this challenge and while it does play an important role, particularly in tackling platform manipulation, governments must play a part in addressing the broader issue,” said Pickles in his posted statement.

“While policy proposals may differ, it is clear that this is not the time to curtail online public conversation and the values that underpin the open Internet.”