British authorities have not found evidence linking Khalid Masood to terror groups.
Facebook, Google, Microsoft and Twitter met with ministers following the London terror attack last week.
Authorities won't confirm nor deny reports that a gate was left undefended while a policeman was being helped.
Official says Khalid Masood's motivation may never be known.
A British-born convert to Islam, Masood had racked up a string of convictions, but none for terrorism-related offences.
Just as we oppose those who bring terror to our streets, we should not allow others to exploit terrorism for evil either.
The U.K. has been on 'severe alert' since 2014, meaning an attack is highly likely.
The man named as French national Mohamed R, was driving at high speed down Antwerp's main shopping street with weapons in his car.
"The problem we have nowadays is this form of low-cost terrorism," the National Front leader said.
May also vowed that Parliament would continue as normal, despite the attack.
Buhari led African leaders in expressing solidarity with the victims of the London attack.
Wes Streeting, a London MP, said Trump Jr. was a "disgrace" for using the attack for "political gain."
Beata Szydło says the assault vindicated Warsaw's refusal to take in refugees.
Police searched addresses in London, Birmingham and elsewhere after the attack that left three dead, plus the attacker.
Rob Lyon describes how he survived an attack in the heart of British democracy.
The hashtag has been used more than 60,000 times since Saturday night.