Obama departs after signing arms pact

US President Barack Obama has left the Czech capital Prague, a day after signing a major nuclear arms reduction treaty with his Russian counterpart Dmitry Medvedev.

Earlier, Obama wrapped up his stay in the Czech Republic by holding private talks with his host, President Vaclav Klaus, later dining with him and other leaders from 10 Central and Eastern European nations.

Obama will host a nuclear security summit in Washington on Monday and Tuesday. He will meet with leaders of more than 40 countries with the expectation of issuing a joint statement on the challenges and importance of nuclear security.