If "Boots On The Ground" Is The Definition Of War, Then Why Did Obama Invoke The War Powers Res.?

If "Boots On The Ground" Is The Definition Of War, Then Why Did Obama Invoke The War Powers Res.?: "If the Obama administration's definition of war, as it pertains to Libya is having 'boots on the ground' there, then why did Obama cite/invoke the War Powers Resolution back in March, given that they say that we never had boots on the ground there, nor were going to?

Secondly, if Obama cited/invoked the War Powers Resolution because we would be hitting Libya with air strikes, and airstrikes/predator drones constitutes warfare (hence the need for Obama to invoke the WPR before attacking Libya), then we are still at war with Libya, and therefore after 90 days Obama will have to get Congressional approval to contine U.S military involvement, or else let the other coalition partners do all of the airstrikes."