Washington ( CNN ) The House of Representatives ' Sergeant at Arms said Thursday that Congress was `` never in danger '' from a plot by a United States citizen to attack the U.S. Capitol , but that officials are still monitoring the situation . In an email obtained by CNN that was sent to all House members and staff , Sergeant at Arms Paul Irving says that `` law enforcement was diligent from the onset and the FBI was able to quickly identify the threat , investigate , and make an arrest . '' `` The public , and in particular the Congressional community , was never in danger during the investigation . The United States Capitol Police ( USCP ) remains in close coordination with the FBI and my office continues to monitor the situation , '' Irving writes . `` We will keep you informed of any important developments that may arise . '' Irving also urges the Capitol community to `` maintain vigilance and security awareness at all times . '' `` I know you have heard it before , but it bears repeating today : if you see something , say something , '' he adds . The email comes just the day after the FBI successfully foiled a plot to attack the U.S. Capitol that was being developed by Christopher Lee Cornell , a 20-year-old Ohioan who was allegedly inspired by ISIS . The incident is the latest to highlight the threat posed by radicalized young men used by terrorist groups to carry out attacks in their own countries . The terrorists in France last week became increasingly radicalized while in prison before traveling to Yemen , where at least one met with the American jihadist Anwar al-Awlaki , a notorious al Qaeda cleric . The brothers ' travel to Yemen and intelligence reports that one also traveled to Syria turned the West 's worst fears — foreign fighters returning to the West to carry out attacks — into a grisly reality . And Maine Sen. Angus King , a member of the Senate 's intelligence and armed services committee , said on Thursday echoed intelligence assessments that `` lone wolf '' terrorists are the `` toughest '' threat to counter . `` The real weapons of mass destruction today are unemployed 22-year-olds who fall for this radical ideology and we 've got to figure out how to counter that , '' he said on CNN 's `` New Day . '' Sen. King on torture report : 'This is not America ' But he disagreed with his Republican colleagues , most notably Sen. John McCain ( R-Arizona ) , who argue that the U.S. needs to ramp up its military effort against ISIS and other terrorist organizations . `` We 've been in the stamping out business for the last 12 or 13 years and it has n't worked all that well , '' King said . `` Part of the problem is the more we , the U.S. and the West , are active — particularly with troops on the ground — the more it becomes a recruiting tool for the extremists . '' Instead , King said the U.S. needs to address what he called a `` deeper question '' : figuring out how the U.S. can combat the radical ideology spread increasingly online by extremists like ISIS and al-Qaeda . King pointed to a program being developed in the United Kingdom , where officials are working to `` de-radicalize or anti-radicalize '' their prisons , which can be hotbeds of extremist recruitment . Even ISIS , which now controls swaths of territory in Iraq and Syria and seeks to inspire the lone wolf attacks U.S. officials are most concerned about , was reportedly formed from an American military prison in Iraq , Camp Bucca , according to The Guardian . There , Abu Bakr al-Baghdadi met the men who would years later become the branches of ISIS 's senior leadership . King stood firm against calls from McCain and other Republican hawks like freshman Sen. Tom Cotton ( R-Arkansas ) who are calling on President Barack Obama to escalate the military fight against ISIS . And American troops certainly should n't be the ones `` rooting them ( ISIS ) out door to door in Mosul , '' a city ISIS captured in Iraq . RELATED : Tom Cotton on terror threat : 'We have to win on offense ' `` We are not going to be able to take them out by killing them one at a time . It 's not going to work , '' King said . `` We 've got to go deeper than just police , FBI , CIA and military . We 've got to talk about how do we stop this movement toward radicalization because otherwise this is going to be a 100-year war . '' Obama and U.K. Prime Minister David Cameron made it clear in an opinion piece published Thursday that they are closely watching the threat of lone wolfs , vowing not to be `` cowed by extremists , '' whether they come in the shape of terrorist groups or `` lone fanatics . '' Reacting to the foiled Ohio plot in an interview with NewsMax , potential 2016 GOP presidential candidate Texas Gov . Rick Perry made a quick connection between terrorism and border security , one of his top issues . Perry said there is `` very good intelligence '' that the south Texas border with Mexico could allow `` individuals '' to come into this country . `` Americans will sleep better knowing that their government is actual doing their constitutional duty , '' Perry said .
After an Ohio man 's alleged ISIS-inspired plot was foiled by the FBI , King says the U.S. needs to counter radicalization . More than just ramping up the U.S. military effort , King pointed to `` unemployed 22-year-olds '' as the greatest threat . King 's comments also come after the Paris terror attacks , carried out by young men who were radicalized in prison .