In an embarrassing open mic moment, U.S. President Barack Obama accidentally broadcast a private conversation with Russian President Dmitry Medvedev.

At a nuclear security summit in Seoul, the two were quietly discussing missile defense before a meeting with the press. Unaware that his microphone was live, Obama explained that certain issues could be solved if he were given some space. 

Yeah, I understand, responded Medvedev. I understand your message about space. He was about to say more, it seems, but the U.S. president cut him off.

This is my last election, said Obama. After my election I have more flexibility.

Medvedev then promised he would relay the message to Prime Minister Vladimir Putin, who will assume the Russian presidency in May.

Conservative commentators and political opponents immediately jumped on Obama's statement. In an article for Fox News, Karl Rove said that Mr. Obama is in effect saying he is ready to do something the Russians will like but that the American people won't. Mr. Obama has shown Russian leaders, and now the entire world, weakness.

Medvedev is meanwhile being mocked in Russia, where critics are trashing him for his apparent deference to Putin.

The controversy continued when U.S. Republican presidential candidate Mitt Romney used strong words during a Monday interview with CNN's Wolf Blitzer. After criticizing Obama for making shady promises, Romney said that Russia is without question our number one geopolitical foe.

On Tuesday, Medvedev ridiculed those comments, saying they smacked of Hollywood and evoked a Cold War mentality. It's 2012, not the mid-1970s, and whatever party [Romney] belongs to, he must take the existing realities into account, he said during a press conference in Seoul.

During Monday's conversation between Medvedev and Obama -- including their private, 90-minute conversation preceding the gaffe -- the two leaders were discussing a NATO anti-ballistic shield system that would be installed in Poland and the Czech Republic to guard Europe against nuclear threats, specifically from Iran. The defense architecture was first proposed by George W. Bush, and former U.S. Defense Secretary Robert Gates continued leading negotiation efforts after Bush left office.

The plans were overhauled by Obama in 2009. He claimed the changes were based on updated intelligence about Iran's capabilities, while critics argued that he was downgrading the program in order to appease Russia at the expense of Poland and the Czech Republic.

In a video conference with Russian reporters on Monday, NATO Secretary General Anders Fogh Rasmussen confirmed that the plans were still in motion. [I]t is our intention to declare what we call an interim capability of the NATO system, he said. This is part of the first phase of a development of the NATO missile defense system.

Moscow is opposed to the defense plan; officials there say the installation of the shield could have a direct impact on Russia's own nuclear capabilities, undermining their powers of deterrence.

Putin, who won the presidential election this year amid claims of vote-rigging, corruption and repression, has made missile defense a cornerstone of his platform. He has plans to increase nuclear spending through 2020. This is a threat to Obama's 2011 START treaty, which he pushed through Congress in late 2010 in order to speed up bilateral nuclear disarmament.

Once Putin begins his third term as Russia's president, he will meet with Obama to continue discussions.