US President Donald Trump has said the leaders of Russia and Ukraine have agreed to his request for a three-day ceasefire and an exchange of prisoners, adding that such a halt to hostilities could be the “beginning of the end” of the long war between them.Ukrainian President Volodymyr Zelensky and Yuri Ushakov, Russian President Vladimir Putin’s foreign affairs adviser, both confirmed the agreement. “I asked and, President Putin agreed. President Zelensky agreed – both readily,” Mr Trump said as he departed the White House to attend a dinner at his Virginia golf club. “And we have a little period of...