The UK is going through a "dark chapter" facing the terrorist threat, a Government minister hailed a hero after the Westminster attack said.
Tobias Ellwood, who tried in vain to save the life of Pc Keith Palmer after he was stabbed while on duty in the Palace of Westminster, paid tribute to the police for their work in a country "that seems to be getting more dangerous and more volatile".
The Defence Minister said the threats faced by the UK were not going away and involved not just terrorism but "resurgent nations challenging the world order".
Mr Ellwood, who has lobbied within government for extra funding for the armed forces, said: "There are some big questions, wider questions, about what we do because this terrorist attack - non-state, caused by Daesh - they are not going away.
"These attacks will continue unless we step forward and actually participate, become more pro-active in dealing with what is a very changing and dark chapter that we are enduring."
The former Army officer's own brother Jonathan was killed in the 2002 Bali terror atrocity.
He told BBC Radio 4's Today: "From 2002 to today, extremism is still there.
"We are still not able to better understand why people with a scant understanding of Islam are able to be recruited with a false promise of a fast-track to paradise.
"Until that is grasped, until we can better ensure that the peaceful religion of Islam is better understood - probably at a very younger age - so these people aren't recruited, this threat will continue."
The threats faced around the world meant "the relative peace that we have had for the last three or four decades is going to be challenged".
"We are in a difficult time at the moment, there's no doubt about it," he said.
Mr Ellwood was walking through the Palace of Westminster when Khalid Masood ploughed into pedestrians on Westminster Bridge before fatally stabbing unarmed police officer Pc Palmer a year ago.
He praised the work of the police on duty that day: "They were the ones that were defending Parliament and us, huge tribute to them.
"They get up every day, they don't know how their day is going to unfold."
He added: "They are the heroes."