Russian and Ukrainian negotiators began talks in Istanbul on Tuesday, and Turkish President Tayyip Erdogan told them that progress would pave the way for a meeting of the countries' two leaders since the time had come for concrete results.
In a televised speech to the negotiators ahead of their first discussions in more than two weeks, Erdogan called for an immediate ceasefire in the war that began last month when Russia invaded Ukraine.
"It is up to the sides to stop this tragedy. Achieving a ceasefire and peace as soon as possible is to the benefit of everyone. We think we have now entered a period where concrete results are needed from talks," he said.
"The negotiating process, which you have been carrying out under the orders of your leaders, has raised hopes for peace."
The Ukrainian embassy in Ankara said the delegation heads had begun talks and discussions would follow between the full delegations.
Foreign Minister Dmytro Kuleba said on Monday Ukraine's most ambitious goal at the Turkey talks this week was to agree a ceasefire. A senior U.S. official said Russian President Vladimir Putin does not appear ready to make compromises to end the war.
NATO member Turkey shares a maritime border with Ukraine and Russia in the Black Sea, has good ties with both and has offered to mediate the conflict. While calling Moscow's invasion unacceptable, Ankara has also opposed the Western sanctions.
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President Donald Trump said on Saturday he will raise a temporary tariff from 10 per cent to 15 per cent on US imports from all countries, the maximum level allowed under the law, after the US Supreme Court struck down his previous tariff programme.
The move came less than 24 hours after Trump announced a 10% across-the-board tariff on Friday after the court's decision. The ruling found the president had exceeded his authority when he imposed an array of higher rates under an economic emergency law.
The new levies are grounded in a separate but untested law, known as Section 122, that al