Russia has deployed the advanced S-400 anti-aircraft missile system in Crimea, as tensions with Ukraine continue to escalate. The deployment comes after Russia seized three Ukrainian navy vessels on Sunday. Moscow and Kiev have traded barbs, with Russian President Vladimir Putin accusing his Ukrainian counterpart of plotting the standoff to boost his popularity ahead of elections. While Petro Poroshenko has accused Putin of seeking to annex Ukraine and urged NATO to send warships to the Sea of Azov. For more on these rising tensions, Sarah Morice has this report.