"We're going to continue to stand our ground, " he told a business group in a speech in Seoul Friday, saying the U.S. doesn't bluff on security matters.

WSJ: U.S., South Korea Offer North Talks, and a Warning

But given the mess both Greece and the euro are in, the threat that Athens could yet call the eurozone's bluff won't go away.

CNN: What if Greece can't manage payback?

It's like Call My Bluff without the cleverness, but it doesn't actually fit in anywhere.

BBC: Liar