I believe the NDAA gives the US military the authority to detain even US citizens they classify as “belligerents” - so how much MORE the authority to detain a foreigner (unless Obama can prove he naturalized as a US citizen at some point) who actually qualifies as an enemy combatant through objective measures such as:
1. funding terrorists
2. arming terrorists
3. training terrorists
4. giving terrorists safe haven
5. propagandizing/recruiting for terrorists
6. belonging in a terrorist organization
7. securing the release of terrorists
8. falsifying government records to make terrorists appear to not be terrorists, to keep them from being arrested/detained/brought to justice
9. aiding in terrorists’ infiltration into the country by thwarting the nation’s due diligence
Executive power and military power under the Constitution is given to the president. It would be ludicrous to think the president could be arrested by subordinates under powers derived from him.
More to the point, the Constitution makes the President C in C. No law can override that.