Donald Trump has said Russia is "laughing their asses off" at what he claims is the "discord, disruption and chaos" gripping the US.
In yet another series of tweets designed to distance his 2016 election campaign from allegations of Russian interference, Mr Trump repeated his insistence that there had been "no collusion".
He tweeted: "I never said Russia did not meddle in the election, I said 'it may be Russia, or China or another country or group, or it may be a 400 pound genius sitting in bed and playing with his computer'
"The Russian 'hoax' was that the Trump campaign colluded with Russia - it never did!"
:: Lavrov: US indictments against Russians 'just blabber'
President Trump later added that if Russia had been attempting to interfere with US politics, it had already succeeded.
"If it was the GOAL of Russia to create discord, disruption and chaos within the U.S. then, with all of the Committee Hearings, Investigations and Party hatred, they have succeeded beyond their wildest dreams," he said.
"They are laughing their asses off in Moscow. Get smart America!"
The posts came after Mr Trump criticised the FBI for missing "all the many signals" that could have prevented the Florida school shooting - and linked the oversights to the Russia investigation.
The agency received a tip last month that suspected gunman Nikolas Cruz had a "desire to kill" and access to guns and could be plotting an attack , but acknowledged that agents had failed to investigate.
Mr Trump said late on Sunday: "Very sad that the FBI missed all of the many signals sent out by the Florida school shooter. This is not acceptable.
"They are spending too much time trying to prove Russian collusion with the Trump campaign - there is no collusion. Get back to the basics and make us all proud!"
The President was tweeting in the aftermath of an emotional anti-gun rally in Fort Lauderdale, Florida , some 25 miles from the school where 17 people were killed on Wednesday.
One survivor of the attack at Marjory Stoneman Douglas High School in Parkland used the Twitter to call out Mr Trump over the $30m his election campaign received from the National Rifle Association (NRA) in 2016.
Addressing the crowd, Emma Gonzalez said: "If the President wants to come up to me and tell me to my face that it was a terrible tragedy and how nothing is going to be done about it, I'm going to happily ask him how much money he received from the NRA."
More protests over US gun control laws are still to come, with the Network for Public Education and the American Federation of Teachers calling on students, teachers and administrators to organise demonstrations for 20 April - the anniversary of the 1999 shooting at Columbine High School in Colorado.