Russian President Dmitry Medvedev will take...

The summit, bringing together more than 40 heads of state, will focus mainly on the vulnerability of nuclear materials and securing them against the threat of terrorists" acquisition.

After the summit in Washington, Medvedev will pay official visits to Argentina and Brazil.

Argentinean trip is scheduled for April 14-15. In Brazil the president will take part in the BRIC countries summit along with Brazilian President Lula da Silva, Indian Prime Minister Manmohan Singh and Chinese President Hu Jintao.

The meeting of BRIC leaders in Brasilia on April 15-16 will focus on improving the current global economic situation and strengthening joint cooperation.

MOSCOW, April 5 (RIA Novosti)