Trump's announcement follows a war of words with former Russian president over social media.

Trump's announcement follows a war of words with former Russian president over social media.

At least 100 people are involved in the search operations at the world's largest underground copper mine.

At least 100 people are involved in the search operations at the world's largest underground copper mine.

At least three are killed in several regions of Russia while fire breaks out at an oil refinery in central Russia.