When asked by a reporter if ISIS had British, German and Italian underground cells like the ones that carried out the deadly March terrorist attacks in Brussels, Clapper, the director of national intelligence, said, "Yes they do."
Clapper added, "We continue to see evidence of plotting on the part of ISIL in (the UK, Germany and Italy)." ISIL is the administration's preferred acronym for ISIS.
He was speaking at a reporters' breakfast held by the Christian Science Monitor newspaper.
Matthew Levitt of the Washington Institute for Near East Policy told CNN that reports of ISIS activity in these countries "is not new" but added "it's new that Clapper is saying it."
Levitt, the former deputy assistant secretary for intelligence and analysis at the Treasury Department, said that while the focus has rightly been on France and Belgium, arrests of suspected terrorists were also taking place in the UK and Germany as well.
In a speech in Hanover, Obama said, "These terrorists are doing everything in their power to strike our cities and kill our citizens, so we need to do everything in our power to stop them."
He called ISIS "the most urgent threat to our nations" and while he acknowledged Europe's contribution to the counter-ISIS campaign he added, "Europe, including NATO, can still do more."
Germany has provided trainers and financial assistance to local forces but its military is not involved in airstrikes against ISIS in Iraq and Syria.
Obama underscored the need to share intelligence among allies, saying "If we truly value our liberty, then we have to take the steps that are necessary to share information and intelligence within Europe, as well as between the United States and Europe, to stop terrorists from traveling and crossing borders and killing innocent people."
Levitt said that Europe's "biggest problem is a lack of seamless intelligence sharing and collaboration."
Clapper also added that ISIS has "taken advantage to some extent of the migrant crisis in Europe, something which the nations I think have a growing awareness of."
Obama during his visit with Chancellor Angela Merkel, lauded her stance on refugees, saying "Chancellor Merkel and others have eloquently reminded us that we cannot turn our backs on our fellow human beings who are here now, and need our help now."
Merkel has been criticized at home and abroad for her welcoming policies towards Syrian refugees, criticism that has increased following the terrorist attacks in Paris and Brussels.
Frank Cilluffo, director of George Washington University's Center for Cyber and Homeland Security, told CNN that all of Europe faces the threat of ISIS-linked operatives infiltrating the refugee flow.
"Given the significant number of foreign fighters from all over Europe that have traveled to Syria and Iraq to join ISIS, it's not surprising that some of them are coming back," he said.