US Vice President Joe Biden said the current US administration "is treading cautiously on Syria after what it sees as Washington's past errors in the Iraq invasion and occupation." Speaking in an interview with Rolling Stone magazine published Thursday, Biden considered that President Barack Obama and his team had helped restore America's image in the world, saying "we don't want to blow it like the last administration did in Iraq, saying 'weapons of mass destruction.'" "The one lesson we learned from Iraq and the last administration is... How can I say it? In managing the affairs in Iraq, they destroyed every institution. There was no structure left. There wasn't even a Department of Public Works," Biden told the magazine. "And we know we can fix that, if we're willing to spend a trillion dollars and 160,000 troops and 6,000 dead, but that we cannot do," he added, in reference to the US troop deployment and toll in blood and treasure in Iraq. On the use of chemical weapons in Syria, the U.S. Vice President said "We know that there have been traces found of what are probably chemical weapons." "What we don't know yet -- and we're drilling down on it as hard as we can -- is whether they were accidentally released in an exchange of gunfire or artillery fire, or blown up or something." He also stressed that it remained unclear who owned the weapons and used them at which point in time. Biden stressed that once the use of the chemical weapons has been verified, Obama would likely make a "proportional response in terms of meaningful action." Meanwhile, US Defence Secretary Chuck Hagel said the problems in the Middle East region, including the crisis in Syria and Iran's nuclear ambitions, require "political, not military solutions." "The most enduring and effective solutions to the challenges facing the region are political, not military," Hagel was quoted by the AFP as saying in a speech at the Washington Institute for Near East Policy. He added that "America's role in the Middle East is to continue to help influence and shape the course of events-using diplomatic, economic, humanitarian, intelligence and security tools in coordination with our allies." Hagel said "the escalation of violence in Syria threatens to spill across its border, considering that Iran's nuclear program and its support to Syria and Hezbollah pose real threats to the US that must be addressed through "coalitions of common interests" including Israel and other allies in the region