WASHINGTON- President Barack Obama and Turkish President Tayyip Erdogan spoke by phone on Tuesday about the need to de-escalate tensions with Russia after Turkey shot down a Russian warplane near the Turkish-Syrian border, the White House said. Obama expressed 'US and NATO support for Turkey's right to defend its sovereignty,' the White House said in a statement. 'The leaders agreed on the importance of de-escalating the situation and pursuing arrangements to ensure that such incidents do not happen again,' the statement said.