Trump tweets about 'loser terrorists' after London Underground terror attack

President Donald Trump condemned "loser terrorists" in a series of tweets after a bomb exploded on a London Underground train Friday morning.

"Another attack in London by a loser terrorist," Trump tweeted. "These are sick and demented people who were in the sights of Scotland Yard. Must be proactive!"

It is unclear what the president meant by "in the sights of Scotland Yard" - referring to London's police force - as no suspects have been publicly identified at the time of his tweets.

Posts on Twitter Friday morning said that a "bag exploded" at Parsons Green, a station on the District Line in west London. Police have confirmed the device was an improvised explosive device.

In his tweets, Trump called for dealing with terrorists "in a much tougher manner" - such as cutting off internet recruitment.

"Loser terrorists must be dealt with in a much tougher manner. The internet is their main recruitment tool which we must cut off & use better!" Trump tweeted.

The president also addressed domestic and international security, tweeting about his controversial travel ban and the ongoing fight against ISIS.

"The travel ban into the United States should be far larger, tougher and more specific-but stupidly, that would not be politically correct!" Trump tweeted.

"We have made more progress in the last nine months against ISIS than the Obama Administration has made in 8 years. Must be proactive & nasty!"