Republican presidential nominee Mitt Romney is expected to make a major foreign policy speech in the next few days that supporters say will reestablish the nation's international credibility.
On Fox News Sunday, Ryan pounced on Obama's foreign policy record, especially over the differing reports about how four Americans were killed in the recent attack at the U.S. Consulate in Benghazi, Libya.
Ryan said he backs a congressional investigation because the Obama administration's response has been "slow, confused and inconsistent."
"Obama's foreign policy is unraveling before our eyes and tv screens," he said.
Ryan said Romney will focus on a policy of "American strength versus what I would articulate or claim is one of weaknesses we're seeing as the ugly fruits of the Obama foreign policy unravel around the world."
He argued that Iran is closer to a nuclear weapon and is largely ignoring promises by Obama to take action if the country moves forward, while Russia continues thwarting the United States.
Ryan called Iran "the biggest threat we have today" and said the president's plan lacks credibility.
Iran would be more willing to work toward a peaceful resolution if Iranian officials believed that Obama was serious about stopping the country from obtaining nuclear weapons, he said.
"A nuclear weapons capability is what we have to stop" in Iran, he said.
The major difference between Obama and Romney, Ryan argues, is credibility.
As president, Romney will "speak with credibility." That means "not establishing daylight between our allies, especially Israel," Ryan added.
That difference is, "when we say what we're going to do, it is believed," he said.
Ryan said President Obama has moved his international policies toward the GOP's in recent weeks, but added that the shift is "built upon a mountain of non-credible actions."
Syria is a good example, "when you hesitate, when don't speak with clarity, when you don't project your confidence in American values it projects weakness and equivocation," Ryan said.
"When you project weakness like this, bad things happen and look at what is going on around the world."