Kate Adie introduces dispatches on Iran, Ukraine, South Africa, Portugal and Hong Kong.

As the world nervously watches the developments between Iran and Israel, Lyse Doucet reflects on the rise of Iran's Supreme Leader, Ayatollah Ali Khamenei. Since coming to power three decades ago, he has managed to avoid taking Iran into an all-out war - could that change as tensions continue to rise?

A missile attack in the Ukrainian city of Chernihiv this week laid bare the weakness of the country’s air defences. Depleted ammunition supplies, as well as a worsening situation on the frontline, have heightened fears that the tide is continuing to turn against Ukraine in its war with Russia. Sarah Rainsford reports from Kharkiv.

South Africa is preparing to go to the polls, and for the first time since the end of white-minority rule, the governing ANC party is predicted to get less than 50 per cent of the vote. As in many other countries, immigration is high on the list of many voters’ concerns. Jenny Hill reports from the border with Zimbabwe.

Next week Portugal marks the 50th anniversary of the Carnation Revolution and its transition to democracy. Simon Busch met some of the men who joined the resistance against the country's former dictator Antonio Salazar, to find out what they think about politics in Portugal today.

And exotic birds have adapted to live alongside humans in some of the world’s major cities – and in Hong Kong it's yellow-crested cockatoos that you might see swooping through the skyline. Stephen Moss tells the story of why they’re now thriving.

Series producer: Serena Tarling