Thursday, U.S. President Barack Obama and Russian President Dmitry Medvedev will sign a treaty to cut both countries' inventory of nuclear weapons. The ceremony will take place in Prague.
The two leaders will meet in the Czech capital, where one year ago, President Obama talked about his goal of a nuclear-free world.
After a one-on-one meeting, the U.S. and Russian presidents will sign an accord that reduces their countries' nuclear stockpiles by 25 to 30 percent, leaving each with about 1,500 strategic nuclear weapons.
Joseph Cirincione, president of the Ploughshares Fund, a nuclear weapons policy organization, says that number is a nearly 50-year low. But he says the treaty's most important provision renews verification procedures which had lapsed in December, when the 1991 START I treaty expired.
"So what this does is restore the U.S. ability to get intelligence on Russia's weapons, and vice versa," said Joseph Cirincione. "And that is what military planners want. They want knowledge, they want predictability, they want stability in that strategic relationship."
Frank Gaffney helped shape U.S. nuclear policy during Ronald Reagan's presidency in the 1980's. He says Mr. Obama is making a dangerous mistake by voluntarily reducing the size of the U.S. nuclear arsenal.
"I cannot imagine that North Korea or Iran, for example, are anything but emboldened by what they see as the abject weakness of this government," said Frank Gaffney.
Former British defense secretary Des Browne says the U.S. and Russia have a responsibility to lead the world's non-proliferation efforts.
"The United States and Russia, between them, have 95 percent of the nuclear weapons in the world, and if we are genuinely to make progress on disarmament, then the onus lays on these two countries," said Des Browne.
President Obama, in his March 26 announcement, said the agreement shows the depth of the U.S. commitment to leading the effort to rid the world of nuclear arms.
"And we've demonstrated the importance of American leadership - and American partnership - on behalf of our own security, and the world's," said President Obama.
The signing of the new START treaty is part of several weeks of intense activity on non-proliferation issues. Earlier in the week, Mr. Obama unveiled his nuclear posture review, in which he said preventing proliferation and terrorism are at the top of the U.S. nuclear agenda for the first time.
Next week, at a nuclear security conference in Washington, the heads of state of 47 countries are expected to discuss non-proliferation issues. And the nuclear Non-Proliferation Treaty review conference takes place next month in New York.