For some insight on this, I am joined by Su Xiaohui, the Deputy Director of the Department of International and Strategic Studies at the China Institute of International Studies.

Q1: Trump's tweet seems to be quite different from the stance of Barack Obama.  In 2009, the president made a famous speech in Prague, calling for the elimination of nuclear weapons. How do you view Trump's message? 

Q2: Putin seems to be exercising restraint after Trump's controversial speech.  How do you interpret that?

Q3:  Russia and the US are at odds over Syria and Ukraine, but Cold War-style nuclear tensions have greatly eased in recent years. Moscow and Washington signed the New START nuclear treaty in 2010, which reduced strategic weapons and delivery systems. Now comes the tweet, the second brusque comment from Trump about atomic weapons in two days. Despite the fact there's clarification that there would not be an arms race,  with Trump due to take office in January, is nuclear tension possible?