Russia and Turkey failed to reach an agreement to bring Ukrainian grain to countries that desperately need it, at a meeting in the Black Sea resort of Sochi. What are the obstacles - and the implications for global food security? The Global Jigsaw team brings together Russia, Ukraine, Turkey, Middle East and Africa experts to assess what could happen next.

As a US territory, Puerto Rico uses the dollar, its people are US citizens and they can move freely back and forth. However, it isn’t a US state, and its residents can’t vote in presidential elections or for members of Congress. The country has a deep debt crisis, high unemployment and has experienced devastating hurricanes and earthquakes. As a result, migration to the US is common, with almost a million more Puerto Ricans in the US than on the island. In 2020, a non-binding referendum resulted in Puerto Rico voting again to become a US state. But will it ever happen? BBC Mundo’s Ronald Avila-Claudio tells us more about his homeland and what the future might hold. Presented by Claire Graham and produced by Owen McFadden for the BBC World Service.

After unilaterally declaring independence in 2008, Kosovo has been recognised by many countries, but not Serbia, which still claims it as one of its provinces. After the break-up of the former Yugoslavia in the 1990s, Serbia cracked down on Kosovo separatists, resulting in a NATO military intervention in 1999. Tensions have remained high and have begun to flare up again in recent years. The majority Albanian population mostly supports independence, but in the northern areas of Kosovo, Serbs are the majority, and many refuse to recognise Kosovan institutions. BBC Serbian reporter Aleksandar Miladinović explains these divisions, and considers if relations between the two countries can ever be normalised.

Nato members agree to support each other if they come under attack. That’s the fundamental purpose of Nato, or the North Atlantic Treaty Organization, formed in the wake of World War II. But how has its remit changed in the seven decades since its foundation? Since Russia’s invasion of Ukraine, more states have sought to join Nato, but its expansion is perceived as a threat by President Putin. James Landale, the BBC's Diplomatic Correspondent, explains how Nato works and what challenges lie ahead for the organisation.

How has Venezuela, home to the world's largest oil reserves, become crippled with food and medicine shortages, hyper-inflation, violence and corruption? Hugo Chavez promised a socialist revolution in the 1990s, using high oil prices to fund his economic developments. However, during his time in power, he became increasingly autocratic and the economy slumped. Following Chavez’s death, Nicolas Maduro, also from the socialist PSUV party, became President but global oil prices began to plummet. The economy went into freefall and controversial elections in 2018 have led to ongoing political unrest. Jorge Pérez, a BBC Mundo journalist, explains how Venezuela descended into chaos.