WASHINGTON - The White House said Wednesday the administration has the authority to order U.S participation in NATO military attacks in Libya without congressional approval. The administration argues in a report sent to Congress Wednesday its actions in Libya are not in violation of the War Powers Resolution, The New York Times reported. "We are acting lawfully," Harold Koh, the State Department legal adviser, told the Times in a joint interview with White House Counsel Robert Bauer. The lawyers argue U.S. forces have not been involved in "hostilities" since NATO took over command of the no-fly zone in Libya April 7 and are only providing a supporting role in the conflict. "We are not saying the president can take the country into war on his own," Koh said. "We are not saying the War Powers Resolution is unconstitutional or should be scrapped, or that we can refuse to consult Congress. We are saying the limited nature of this particular mission is not the kind of 'hostilities' envisioned by the War Powers Resolution." Tensions in Washington over the Libya conflict reflected growing unease over U.S. entanglement in a third conflict in the Muslim world in addition to costly wars in Iraq and Afghanistan and pressure for Obama to clarify the U.S. mission in the North African country. In a document provided to members of Congress Wednesday, the Defence Department laid out the costs of U.S. action and the consequences if U.S. forces were not to participate in NATO operations. "If the United States military were to cease its participation in the NATO operation, it would seriously degrade the coalition's ability to execute and sustain its operation designed to protect Libyan civilians and to enforce the no-fly zone and the arms embargo, as authorized under UNSCR 1973," the Defence Department said. "Cessation of U.S. military activities in support of [Operation Unified Protector] would also significantly increase the level of risk for the remaining allied and coalition forces conducting the operation, which in turn would likely lead to the withdrawal of other NATO and coalition nation participation in the operation. "Furthermore, if NATO had to terminate the operation before the recently agreed 90-day extension [to Sept. 27] because it did not possess the assets and capabilities required to conduct or sustain the operation, then NATO's credibility would be damaged with significant consequences for U.S., European and global security." A bipartisan group of U.S. lawmakers said Wednesday they are suing President Obama for approving allegedly illegal military action in Libya, Politico reported. "With regard to the war in Libya, we believe that the law was violated," said Congressman Dennis Kucinich, a Democrat who heads the group of 10 House members. "We have asked the courts to move to protect the American people from the results of these illegal policies," Kucinich said, adding the suit will contest the Obama administration's "circumvention of Congress and its use of international organizations such as the United Nations and the North Atlantic Treaty Organization to authorize the use of military force abroad." The lawmakers also include Democrats John Conyers of Michigan and Michael Capuano of Massachusetts, and Republicans Walter Jones and Howard Coble of North Carolina, John Duncan of Tennessee, Roscoe Bartlett of Maryland, Ron Paul of Texas, Tim Johnson of Illinois and Dan Burton of Indiana. The action comes one day after House Speaker John Boehner, a Republican, gave Obama an ultimatum to end military action in Libya by Friday, 90 days after operations began.