The latest version of his travel ban, initially announced in a botched late-January rollout, calls for a ban on people entering the US from a short list of terror-prone countries that are also Muslim-majority nations.
"Our thoughts go out to all of those injured in the attack on a train at Parsons Green Station this morning", said Jonathan Arkush - the president of the Board of Deputies of British Jews - in a statement. McMaster did not characterize the president's conversation with May, saying he was not on the call.
Ms May said a major covert investigation was taking place and warned the public of an armed police presence on the transport network and London's streets.
Diplomacy is an art that the American president still can not handle. The latest incident once again reinforces the need for concerted efforts to effectively address extremism and terrorism, which threaten the security of all citizens in their daily lives.
Israel reached out in solidarity with the 18 injured in the west London underground train terror attack on Friday from The State of Israel's official Twitter account. Instead he speculated about the role of the British police in the incident and exploited the violence for a chance at political gain.
In a string of tweets about the London attack, Mr. Trump called for being "proactive & nasty" to fight terrorists.
"According to a translation by Middle East observer Hassan Hassan, the message on the group's propganda page said: "A security source to Amaq: the bombing of the IED in the London tube was carried out by a unit affiliated to the Islamic State", said The Independent report.
British authorities say they have foiled 19 plots since the middle of 2013, six of them since the van and knife attack on Westminster Bridge and Parliament in March, which killed five people.
McMaster didn't answer directly at a White House briefing whether Trump was revealing an intelligence assessment or whether he was just speculating. "Scotland Yard has been a leader, and our Federal Bureau of Investigation has been a leader".
"The threat of terrorism that we face is severe, but by working together we will defeat them".
"I think he means generally that this kind of activity is what we are trying to prevent", McMaster said.
Pressed to explain further, McMaster said that U.S. and United Kingdom agencies are both working to prevent terrorism.
President Donald Trump is calling the explosion in London a "terrible thing". After two terror attacks in the city in June, Trump seized on the moment.