Turkey promised it would ensure that ISIS was defeated in Syria, US President Donald Trump said on Twitter as he continued to underscore the connection between Istanbul and his decision to withdraw US troops from Syria. “President Erdogan of Turkey has very strongly informed me that he will eradicate whatever is left of ISIS in Syria... and he is a man who can do it plus, Turkey is right 'next door.' Our troops are coming home!” Trump said.Outgoing US Secretary of Defense James Mattis on Sunday signed the order to send home the 2,000 US troops stationed in Syria, the US media reported.CNN reported on further details of the link between the decision and Turkey. It provided details of a December 14 telephone call between the two leaders, during which Trump agreed to the pull-out."OK, it's all yours. We are done," Trump reportedly told President Recep Tayyip Erdogan.On Sunday, Trump reported that he had just finished a subsequent phone call with Erdogan and that the two countries were coordinating the US troop withdrawal.“I just had a long and productive call with President Erdogan of Turkey. We discussed ISIS, our mutual involvement in Syria, & the slow & highly coordinated pullout of U.S. troops from the area. After many years they are coming home. We also discussed heavily expanded Trade,” he tweeted.Senator Bob Corker, the influential Republican chairman of the Senate Foreign Relations Committee, said he was "saddened" by Trump's withdrawal decision. "I think he knows he made a mistake," Corker, who is retiring, said on CNN. "The president's tendencies are to dig in and double-down if he knows he has done something that is probably incorrect.”Prime Minister Benjamin Netanyahu said on Sunday that Israel may increase its activity against Iran in Syria in response to the decision."The decision to withdraw 2,000 US troops from Syria will not change our consistent policy: We will continue to act against Iran's attempts to entrench itself militarily in Syria, and to the extent necessary, we will even expand our actions there," he said.“I would like to reassure those who are concerned," Netanyahu continued. "Our cooperation with the US will continue in full and finds expression in many areas: Operations, intelligence and many other security spheres."