Republican presidential contender Ted Cruz, a senator from Texas, speaks with the media on Wednesday, Jan. 6, in Rock Rapids, Iowa. (David Weigel/The Washington Post)

ROCK RAPIDS, Iowa -- Sen. Ted Cruz (R-Tex.) reacted to news of the alleged hydrogen bomb test by North Korea with an indictment of two decades of Democratic foreign policy, warning that any president who didn't "tear up" the nuclear agreement with Iran would risk attacks on American and Israeli cities.

"This underscores the gravity of the threats we are facing right now, and also the sheer folly of the Obama-Clinton foreign policy," Cruz told reporters before a crowded meet-and-greet at the British-themed Union Jack's Grill. "When we look at North Korea, it's like looking at a crystal ball. This is where Iran ends up, if we continue on this same misguided path. It's worth remembering, we're here because of the Clinton administration. The Clinton administration led the world in relaxing sanctions against North Korea. They used the billions of dollars that flowed into North Korea to develop nuclear weapons. Now we're facing a megalomanical manic who may potentially have a hydrogen bomb."

Cruz also derided the Obama administration for giving a job in the State Department and a role in the Iran negotiations to North Korea negotiations veteran Wendy Sherman -- "the one person on Earth who has already messed this up. And sadly, they negotiated essentially the same deal."

Three GOP presidential candidates slammed Democrats in light of North Korea's claims of a successful hydrogen bomb test. House Speaker Paul Ryan (R-Wis.) and White House press secretary Josh Earnest also weighed in on the claims. (Sarah Parnass/The Washington Post)

Asked how a Cruz presidency would respond to North Korea, the candidate said he would pressure China to "cut off their client state," and "to continue to isolate North Korea, to continue to cut off North Korea, to raise the costs of their belligerence." But he warned that "every bad actor would get worse" until Obama was replaced.

"For the remainder of President Obama's term, we're essentially in a Hobbesian state of nature, like 'Lord of the Flies,'" he said.

Near the start of his remarks to more than 150 voters, Cruz sharpened his criticism to a few stark lines.

"We saw last night the consequences of this deal if it is allowed to go forward," he said. "[Iran's] nuclear test may be not be underground, measured by an earthquake. It may be above the skies of Tel Aviv, or New York, or Los Angeles."