( CNN) A handful of top US national security officials said Thursday that Russia is continuing to pursue its efforts to interfere in the US political system and said President Donald Trump has directed them to construct countering election interference a top priority.

The top officials' presence in the White House briefing room amounted to the administration's most significant effort to date to convey that a whole of government effort is being undertaken to combat Russian attacks on US democracy, which Homeland Security Secretary Kirstjen Nielsen said is “in the crosshairs.”

“Free and fair elections are the cornerstone of our republic, and it has become clear that they are the target of our adversaries who attempt … to sow dissension and undermine our way of life, ” Nielsen said.