WASHINGTON — A resolution authorizing American intervention in Libya was approved on Tuesday by the Senate Foreign Relations Committee, hours after members skeptically grilled the administration’s legal adviser over his assertion that airstrikes and other military measures did not amount to hostilities.

The resolution, approved 14 to 5, would allow President Obama to continue for one year the involvement of United States military forces in the NATO-led operation in Libya; it now heads to the full Senate. A similar measure failed in the House last week, underscoring that even in a divided government, the Senate remains a more interventionist body while the House is increasingly dubious about foreign ventures and their cost.

For weeks, tensions have escalated between members of Congress and the Obama administration over the president’s decision not to seek Congressional authorization for the mission in Libya. The Vietnam-era War Powers Resolution stipulates that presidents must terminate unauthorized deployments into what the law calls hostilities 60 days after notifying Congress that they have begun.

In testimony before the committee Tuesday, Harold H. Koh, the legal adviser to the State Department, insisted that the resolution did not apply to Libya, a position that the administration has expressed repeatedly.