For more information on the Nuclear Security Summit, we are joined from Washington by our correspondent Zhu Hua.

1. President Hu Jintao has arrived for the Summit. China's presence has drawn much attention. What's the country's role on strengthening nuclear security worldwide?

2.The US and Russia, which account for more than 90 percent of the world's nuclear weapons, have signed a new nuclear arms reduction treaty. Will this help create a positive climate for the summit?

3. This is a meeting about global security. But what about the security work itself? How does it affect people's daily lives?