Senator Joseph Lieberman addresses the Seventh Annual Christians United For Israel convocation in Washington, D.C. Photo: Maxine Dovere.

U.S. Sens. Joe Lieberman (I-CT) and Jon Kyl (R-AZ), both set to retire next month, criticized U.S. President Barack Obama for relying primarily on sanctions to try to prevent Iran from acquiring a nuclear weapon.

Both senators believe a stronger military threat should be clearly placed on the table. “We have to make sure our threat of military action… is credible to them [and] I’m still not sure it is,” Lieberman said at a discussion organized by the Foundation for Defense of Democracies, according to the Washington Free Beacon.

“I think the Iranian are probably nervous, but not nervous enough,” Kyl said at the discussion.

The two senators said that while sanctions are having a strong effect Iran, they are not impacting Iranian political and military leaders, who are mostly insulated from the effects of the crippling Iranian economy. “The sanctions have been unprecedented and are having an effect on the Iranian economy, but so far not an observable effect on the Iranian regime at all,” Lieberman said, adding that a nuclear Iran will change the balance of power in the Middle East and embolden terrorist groups such as Hezbollah and Hamas.

Lieberman also voiced concern about Egyptian President Mohamed Morsi’s increasingly authoritarian rule and his ties to the Muslim Brotherhood. If Morsi continues down this path, the Obama administration should not “have normal relations” with him, Lieberman said. In terms of the Obama administration’s policy regarding Syrian President Bashar al-Assad, Lieberman called for greater support for Syrian dissidents and argued that “Assad is the number one friend of our number one enemy, Iran,” so his fall would “be a significant body blow to the regime in Tehran.”