Currently the guideline is the War Powers Act which requires the President consult with Congress before engaging in hostilities. It was enacted in response to the unilateral escalation of our involvement in Viet-nam.
In the half a century since the War Powers Act was enacted situations have developed every few years where a President wants to take military action against some foe but fears if he tells Congress word will leak out and undermine the opportunity to accomplish the mission. So Presidents have often acted unilaterally. Each time it sparks a fight that sucks up lots of time and energy and nothing gets resolved. The War Powers Act clearly needs some tweaks.
Presidents ordering military strikes unilaterally is an uncomfortably close step beyond a President using the military to protect his/her own political interest. Even if the Presidents sole motivation is to act in the countries interest a President usually surrounds himself with like minded people. So the decision making process is prone to infection by group think that allows an administration to convince themselves to take a certain course of action without really vetting all the consequences. Who can forget our invasion of Iraq based on the administrations conviction Iraq was building nuclear bombs, which turned out to be completely false.
On the other hand, democracy is like a bureaucracy, it has great difficulty making quick decisions and is lousy at keeping secrets.
As voters we need to demand Congress work out a process that requires the President to consult with Congress that can produce quick, but secret decisions. That probably means the entire Congress cannot be involved.
Here is one possible approach. Set up a protocol for regular meetings between the administration and the small group representing Congress. Those meetings should happen periodically even if no imminent action is planned in order to pre-authorize action by the President for specific types of anticipated possible events.
The meetings should be top secret, they should be recorded and it should be a Federal crime for anyone to say anything about the meeting before any specific military action that requires surprise contemplated at the meeting has occurred or is determined to be no longer feasible.
This is the highest form of national security so any journalist who learns information about the meeting and publishes that information in any form while the action contemplated has yet to be completed can be required by law to reveal the source of their information, and be subject to criminal penalties.
If a leak does occur an independent commission to investigate the leak should automatically be convened, perhaps composed of the members of the intelligence committees of both the house and the Senate, or a panel of Federal Judges.
This needs to be something everyone in Government acknowledges is beyond partisanship. So, to provide public accountability the recordings and transcriptions of the meetings should be publicly disclosed within two years, absent temporary continuance from the Supreme Court based on ongoing, immediate security needs.