President Barack Obama, right, toasts with Russian president Dmitry Medvedev, left, and Czech Republic president Vaclav Klaus at the Prague Castle in Prague Thursday, April 8, 2010. The two leaders signed the New START treaty later in the day.(AP Photo/Alex Brandon)

Photo by: Alex Brandon

President Barack Obama, right, toasts with Russian president Dmitry Medvedev, left, and Czech Republic president Vaclav Klaus at the Prague Castle in Prague Thursday, April 8, 2010. The two leaders signed the New START treaty later in the day.(AP Photo/Alex Brandon)