Washington ? President Bush on Saturday called the leaders of Russia and Italy to discuss how to check the spread of dangerous weapons and keep them away from terrorists.

Bush also devoted his radio address to the issue of weapons of mass destruction, telling the American people that “the possibility of secret and sudden attack” with such arms “is the greatest threat before humanity today.”

Bush and Russian President Vladimir Putin discussed Bush’s speech last week in which he proposed new ways to halt illicit weapons trafficking, White House spokeswoman Jeanie Mamo said. Bush warned that black-market dealings by the architect of Pakistan’s nuclear weapons program had exposed holes in global enforcement efforts.

Bush wants other countries to spend more on programs aimed at securing vulnerable nuclear arsenals in Russia and other former Soviet-bloc nations. He made no mention of any additional U.S. dollars for the effort.

The Kremlin said Bush and Putin also discussed the results of a series of high-level contacts, including the recent trip to Washington by Putin’s chief of staff, Dmitry Medvedev. Last week he delivered a letter to Bush in which Putin pledged that Russia would remain a “reliable and predictable partner” for the United States.

Bush and Italian Premier Silvio Berlusconi spoke about Libya, whose leader, Moammar Gadhafi, pledged in December to end development of weapons. Berlusconi last week became the first Western government head to visit Libya since Gadhafi announcement.