Poland's foreign minister said the US had told Russia that it would strike Russian targets in Ukraine if Putin were to use nuclear weapons.In an interview with the Guardian, Radosław Sikorski seemed doubtful of Russia's threats about using nuclear weapons, saying: "The Americans have told the Russians that if you explode a nuke, even if it doesn't kill anybody, we will hit all your targets [positions] in Ukraine with conventional weapons, we'll destroy all of them.""I think that's a credible threat," he said. "Also, the Chinese and the Indians have read Russia the riot act. And it's no child's play...