Obama: Iranian arms shipments to Yemen would be a problem

President Obama on Tuesday warned Iran not to deliver weapons to Houthi rebels in Yemen, saying it would be a "problem" if an arms exchange occurred. 
"What we've said to them is that if there are weapons delivered to factions within Yemen that could threaten navigation, that's a problem," Obama said in an interview with MSNBC's Chris Matthews. "We're not sending them obscure messages; we send them very direct messages about it."
The president's comments come as tensions between the U.S. and Iran have risen over the Tehran’s support for Shia rebels in Yemen, complicating the two nations' efforts to finalize a nuclear agreement. 
The U.S. Navy deployed an aircraft carrier to Yemen, where a flotilla of nine Iranian ships is sailing, potentially to provide arms to the Houthi rebels. Administration officials have downplayed the carrier's role, saying it is there to maintain freedom of navigation.
“Right now, their ships are in international waters," Obama said. "There's a reason why we keep some of our ships in the Persian Gulf region and that is to make sure that we maintain freedom of navigation."
An Iranian arms shipment to the Yemeni rebels would violate a United Nations Security Council resolution. White House press secretary Josh Earnest on Tuesday would not say whether the Navy would board the Iranian vessels, but he said the U.S. and its allies are "serious" about enforcing the arms embargo.  
The president encouraged the rebels and pro-government factions to end the conflict and come to a political agreement. 
"It is not solved by having another proxy war fought inside of Yemen and you know, we're indicated to the Iranians that they need to be part of the solution, not a part of the problem," he said.