The US and North Korea have been flexing their military muscles in recent weeks, testing and deploying new missiles.

President Trump has said North Korea is "a big big problem" that he will deal with "strongly". This week he took the extraordinary step of briefing the entire US Senate on American options to deal with the North's nuclear programme, as American troops conducted live-fire exercises near the North Korean border. Senators said the briefing was "sobering".

Here, David Aaronovich gets his own briefing, from one of America's top former diplomats in the region and from experts in Beijing and Seoul.

CONTRIBUTORS:

Daniel Russel: President Obama's Assistant Secretary of State for East Asian and Pacific Affairs, now Diplomat-in-Residence at the Asia Society Policy Institute

Yanmei Xie: Chinese foreign policy analyst, formerly with the International Crisis Group, now with Gavekal Dragonomics.

Jenny Lee: Opened the first western news bureau in North Korea, now with the Wilson Centre in Seoul

Producer: Neal Razzell