Presidential candidate John Kerry plans to criticize a U.S.-Russian treaty to cut nuclear weapons in his first Senate speech since undergoing prostate cancer surgery three weeks ago.

Kerry says the Moscow Treaty, which was signed by President Bush and President Vladimir Putin in Moscow last May, "is just the latest example of an area where a better and stronger kind of leadership is needed" to protect homeland security.

The treaty requires the United States and Russia to cut their active nuclear arsenals by two-thirds over the next 10 years.

"I worry about this treaty not because one side might cheat but because, with all its weaknesses, it could increase the opportunities for nuclear theft and terrorism by expanding Russian stockpiles of nuclear materials," he said in remarks prepared for delivery Wednesday on the Senate floor and provided to The Associated Press.

Kerry spokesman David Wade said Kerry, who is recovering from Feb. 12 surgery to remove his prostate gland, will wait to see what amendments are added to the treaty before deciding whether to vote to ratify it. Kerry supports language that would strengthen verification so the world will know the weapons are dismantled or stored and properly supervised.

Officials in the Bush administration "say the Moscow Treaty puts an end to old suspicions and embraces a new Russia," Kerry said. "But they won't acknowledge that this new Russia is also home to organized crime, declining military morale, crumbling infrastructure and economic woe."