All legislative Powers herein granted shall be vested in a Congress of the United States . . . .Next, consider Article II, Section I:
The executive Power shall be vested in a President of the United States of America. . .Do you notice the difference? The power of Congress is not stated as "the legislative power shall be vested in a Congress of the United States." In contrast to the executive branch of government, the power of the legislative branch is granted as specific enumerated powers. Of course, the enumerated powers are provided in Article I, Section 8. Congress is supposed to only have the legislative powers specifically written and thereby granted by the Constitution.
In contrast, the President has the executive power and there is no specific enumeration of the executive powers. It seems the President has all the executive powers we might think to enumerate. Of course, this does not mean the power of the Presidency is unchecked. After all, the power to tax and spend is not an executive power but a legislative power.
There seem to me at least 2 reasons why I should find this observation important. First, the contrast emphasizes that constitutionally the power of Congress is specifically enumerated and granted by We The People. If a legislative power has not been specifically granted in the Constitution, then Congress should be thought to not have that legislative power.
Second, in the arena of national security I think we should take note of whether or not Congress has been specifically granted enumerated legislative powers in this arena. As I read through Article I, Section 8 it seems to me Congress has specifically been granted the constitutional legislative power to create and finance the means by which the United States protects itself from external threats to the safety of We the People. These specific powers do not seem to directly include the power to choose how these means of national security will be utilized and directed. The specific applications of the means of national security are among the powers of the Presidency.
This said, while Congress does not have enumerated powers to directly constrain Presidential power in the arena of national security, Congress does have significant indirect powers relative to Presidential power. First, Congress taxes and makes appropriations, and in this way Congress can constrain the Presidential power with respect to national security by refusing to fund specific ways in which the means of national security are utilitized. Second, Congress has the power of Presidential impeachment should it find that any of the constitutional powers of the President have been abused by the President.
Perhaps all of this constitutional musing suggests one further insight. When Congressional politicians are seen and heard in public attacking Presidential actions with respect national security, one might suspect the attacks are more self-interested than reflections of a love and commitment to the Constitution. After all, if a Congressional politician thinks the President is using the means of national security inappropriately, shouldn't that politician utilize his legislative power to ask his colleagues in the Congress to tug on the purse strings in ways that the President will not like? Such action would seem to fit the structure of government found in our Constitution. If a politician chooses not to speak legislatively, but instead in the media, perhaps the politician is simply trying to get more face time. If a politician says the President should be impeached, then perhaps he or she should "put up" by formally pursuing that Congressional action.