Sen. Ron Johnson, R-Wis., said Monday that the U.S. needs to examine "how much can we really tolerate" in the face of an ongoing terror threat.

“America is a very tolerant society, we value that ... but in this new era, in this new phase, with this new threat to national security, we really need to ask ourselves very serious questions," Johnson said at the Newseum in Washington, D.C. "How much can we really tolerate? Understanding that paradox of tolerance — if we tolerate too much, our tolerance itself will be ended."

Johnson said the U.S. must be “relentless” in the pursuit of stopping extremists, even after heavy territory losses from the so-called Islamic State.

“We are dealing with something else now," he said.

Johnson said that while child pornography is banned on the Internet, information on how to build homemade bombs and the right truck to use in a ramming attack is available online.

“Al Qaeda, ISIS, Islamist terror has spread, has evolved, has metastasized,” Johnson said, referencing that the U.S. now has troops ready for combat in 19 countries. “And we are entering this new phase, certainly demonstrated by ISIS, where they are using social media in incredibly sophisticated, incredibly effective ways.”

Johnson argued that in order to combat the recruitment, incitement, and training on social media the U.S. must first have a “rational, legal immigration system” that can “assimilate” immigrants.

“We must ask ourselves how many can we accept? How many can we assimilate?” Johnson questioned.

He also argued that one of the biggest “blunders” of the Obama administration was pulling troops out of Iraq, arguing that “one thing we have to be prepared to do is to be relentless in our pursuit in destruction of violent extremists.”

Johnson argued that similarly to the U.S. declaration of war on Japan in 1941, the U.S. needs “an all-out authorization declaration” to end “the generational war.”

“We are not devoting the national resources we need to defend our nation, to keep the homeland safe,” Johnson said.