TULSA, Okla. - While discussing the threat of Iran today to a crowd of about 4,000 people at Oral Roberts University, Republican presidential candidate Newt Gingrich said that defeating Barack Obama was "in fact, a duty of national security."

"Because the fact is, he is incapable of defending the United States," Gingrich said.

Gingrich told the crowd, many of them young students, there was a real threat of an American city being wiped out. Gingrich said the Obama administration refuses to acknowledge radical Islamists.

"All of you should be very deeply concerned about national security. Barack Obama is the most dangerous president in modern American history," Gingrich said.

Gingrich said the Obama administration was demonstrating "willful dishonesty" over describing what motivated the suspected terrorist from Morocco, who was arrested Friday by FBI agents for allegedly plotting to blow up the Capitol.

"Any honest person knows what motivated the person who came here," Gingrich said. "This is not smearing everybody, this is not Islamaphobia. If we can't have honest conversation about radical Islamists and we can't figure out - there is a very specific group of people across the planet - there's a very specific desire to kill us."

Gingrich said the Obama administration was intellectually disarmed and incapable of describing threats that face the United States.

"The president wants to unilaterally weaken the United States, he wants to cut the aide to Israel for its anti-ballistic missile defense, he refuses to take Iran seriously," Gingrich said. "We are in a world that is very dangerous. And I say this to those of you who represent the next generation because you're going to bear the consequences."