The United States will work with Turkey to hold Syria accountable for what U.S. officials believe was a deliberate act of shooting down a Turkish fighter jet, the White House said Monday. Spokesman Jay Carney said the United States supports Turkey as it investigated Friday's downing of the Turkish airplane and determined its response. “We will work with Turkey and other partners to hold the Assad regime accountable," Carney told reporters aboard the presidential airplane. “We are in close contact with Turkish officials as they investigate." Washington already has condemned the downing of the Turkish airplane. Secretary of State Hillary Clinton on Sunday called it a “brazen and unacceptable act." Pentagon officials said Monday they believed the downing was deliberate. “We don't have the [details] of the decision-making process that led to this aircraft being shot down," said Captain John Kirby, a Pentagon spokesman. “The fact is that it was shot down. We believe it was a deliberate act." “And the Syrian regime needs to answer for it," added Pentagon chief spokesman George Little.