The US Congress could approve legislation imposing news sanctions on Iran in a few weeks. Admiral Mike Mullen, the US chairman of the Joint Chiefs of Staff, says negotiations and sanctions are the preferred methods, but he also mentioned military action as the "last option".

It is quite a change from Barack Obama's outreach in 2009 when he spoke to the Iranian people on Nowruz, the Iranian New Year.

Since then, Tehran has ignored the US president's offer to negotiate, and the White House has been pushing for economic penalties and has increased military activity in the region.

Recently in a nuclear summit in Washington DC, Obama said Beijing would support further sanctions against Tehran by the UN Security Council.

On Wednesday's show we ask: Has the Obama administration changed its tone toward Iran and will a more hard-line approach deter Tehran from its nuclear programme?

Joining the show will be Flynt Leverett, the director of the Iran Initiative at the New America Foundation. It is a nonprofit group that identifies new challenges for the US. We will also have Abbas Milani, a co-director of the Iran Democracy Project at the Hoover Institution, a conservative US think tank.

You can join the conversation. Call in with your questions and comments on Wednesday, April 21, at our live time of 1630GMT. Repeats will be aired at 2130GMT, and the next day at 0230GMT and 1130GMT.