U.S. forces in Syria will leave the country when local forces are capable of keeping the Islamic State in check on their own, Defense Secretary Mark Esper has said. He made it clear that the enduring defeat of the dreaded terrorist outfit remains the mission of the U.S. forces in Syria. U.S. forces in Syria are working in partnership with the Syrian Democratic Forces, which has been a great partner in the sense of providing very capable ground forces," Esper told the House Armed Services Committee Wednesday during a hearing on U.S. policy in Syria and the broader region. "U.S. forces are fighting ISIS from Africa into Afghanistan, Esper said. "The metric we have set out for this in terms of when we could consider redeploying ... would be when we feel confident that local security and police forces are capable of handling any type of resurgence ... of ISIS," he added. Esper told lawmakers the United States already has had success in defeating ISIS, including the destruction of the physical caliphate, the liberation of 7.7 million people who had been living under the caliphate's rule, and a series of successful operations that resulted in the deaths of its leader Abu Bakr al-Baghdadi and a top deputy. Esper also told the House panel that while the National Defense Strategy prioritizes nations such as Russia and China as top security challenges for the United States, vigilance in countering threats posed by Iran and violent extremist organizations remain a priority. The Defense chief listed the Trump administration's priorities in the Middle East - to ensure the region is not a safe haven for terrorists, not dominated by any power hostile to the U.S., and contributes to a stable global energy market. According to Esepr, the six objectives for the U.S. military in the Middle East are Using dynamic U.S. military presence with strategic depth to deter and respond to aggression; Strengthening the defensive capabilities of regional partners; Advancing partnerships and burden-sharing with allies and partners to address shared security concerns; Protecting freedom of navigation; Denying safe haven to terrorists that threaten the homeland; and Mitigating threats posed by weapons of mass destruction. The Defense Secretary had said last month that around 600 U.S. troops will remain in Syria to ensure that ISIS doesn't re-emerge and get money from oil fields. Hundreds of U.S. troops have left northern Syria, and are being re-deployed to Iraq to fight Islamic State terrorists in that country. Pentagon estimates that there are roughly 11,000 ISIS fighters in Syria and Iraq, but they are ineffectual. They are finding it difficult to move people and material around. They have been forced into marginal areas and cut off from sources of funding and recruiting.