ASTANA (Reuters) - Russian President Vladimir Putin s envoy for Syria said on Thursday that there was no reason for U.S. forces to remain in Syria and that Washington s stated reasons for maintaining a military presence there were groundless. Alexander Lavrentiev was speaking in Astana, the capital of Kazakhstan, ahead of a new round of Syrian peace talks between Russia, Iran and Turkey.  Any reasons cited by the Americans to justify their further military presence ... are just excuses and we think their presence must end,  he told reporters. Lavrentiev said the Astana talks would focus on setting the ground for a Congress of Syrian Peoples which Russia plans to host early next year. The sides plan to decide on the date for the congress on Friday, he said. But agreeing a list of delegates will take longer, up to three weeks. Turkey last month objected to the presence of the main Syrian Kurdish group at the congress. 