Something odd is happening in the relationship between Congress and the executive branch regarding the use of military force. For decades, or even longer, countless senators and representatives have complained that presidents are not properly respectful of their constitutional prerogatives in making decisions on employing US military power. And today, most Democrats and a number of Republicans seem to agree that President Donald Trump is an impulsive, erratic, even dangerous commander-in-chief.

Yet even at a time when so many on the Hill argue that the president cannot be trusted, Congress as a whole is showing little inclination to constrain executive authority in the use of force.

Consider two recent examples. First, earlier this month, Trump ordered US forces to attack targets in Syria in response to the alleged use of chemical weapons by Bashar al-Assad’s government. These strikes marked the second time Trump has ordered military attacks against Assad’s regime. Yet even though they represented an expansion of US intervention in Syria, even though they could not be justified on grounds of self-defense, even though they were not plausibly covered by any existing congressional authorization for use of military force, and even though the Barack Obama administration did seek congressional approval when it was considering similar strikes in 2013, the Trump administration has not offered any clear articulation of where it believes its authority to use force in this instance comes from.

This apparent indifference to Congress’s role has elicited some grumbling from individual senators and representatives. But the body writ large has shown little inclination to push back -- by passing resolutions calling on Trump to seek congressional approval for any future strikes against the Syrian regime, by making clear it will not fund future operations not explicitly authorized by Congress, or by otherwise using the legislative tools and authority the Constitution provides.

The same goes for a second example: The ongoing debate about how and whether to limit executive authority in waging the global war on terrorism. For years, congressional observers and other critics have complained that the AUMF passed just after the Sept. 11 attacks -- which has served as the legal basis for US operations against terrorist groups -- is too expansive and has been interpreted too loosely by successive administrations. Today, after numerous false starts, there is a somewhat more tailored authorization under consideration, one that enjoys bipartisan sponsorship.

Yet this new AUMF preserves, rather than challenges, executive dominance in fighting terrorism. It gives the president great flexibility to designate what groups can be targeted with military force, and would force Congress to assemble veto-proof supermajorities to override any such designation.

In sum, the new AUMF affirms the distinctly subordinate role Congress has played since 2001.

At first glance, this deferential attitude seems puzzling, given that members of Congress have consistently voiced unease about the trend toward greater presidential latitude in foreign affairs.

After all, it is not simply Democrats who worry about the president’s proclivity for ill-considered action. It was the Republican chairman of the Senate Foreign Relations Committee, Bob Corker, who warned last year that Trump might blunder into “World War III.” Yet even as Democrats have pushed (without success) legislation seeking to prohibit Trump from unilaterally ordering a preventive strike on North Korea, the overall congressional response has been surprisingly muted.

So what is going on here? There are two principal reasons for this passive attitude -- the first prudential and reasonable, the second more cynical and political.

The prudential reason is that congressional deference since 2001 may simply reflect the diffuse and evolving nature of the struggle the US faces. Terrorists do not respect national borders; new enemies arise and advance as others recede. The US threw core al-Qaeda on its heels in Afghanistan in 2001 and 2002, only to see the proliferation of affiliate groups in Iraq, Yemen, Somalia and elsewhere thereafter.

Since 2014, the US has also faced threats from ISIS -- an al-Qaida splinter group -- and its own affiliates from Libya to Afghanistan and beyond. The threat, then, is amorphous and transnational, and it requires ongoing suppression across an array of geographic fronts.

As a result, the best model for waging the war on terrorism may very well be one in which the executive has primacy in defining the scope of that conflict, with Congress retaining -- but only very selectively using -- the right to step in should that flexibility be misused.

Yet there is also a second factor at work, having far more to do with politics than national security. In recent decades, members of Congress have repeatedly learned that there is often more political risk than profit in standing up and being counted on hard issues involving the use of force.

In 1992, the presidential aspirations of Senator Sam Nunn and several other Democrats were derailed in large part by the fact that they had opposed a successful war against Iraq the year before. In 2004 and 2008, the presidential ambitions of John Kerry, Hillary Clinton and other Democrats were impaired by the fact that they had supported another, much less successful, war against Iraq in 2003.

Elected officials know that votes that subsequently look unwise will be held against them, which naturally predisposes them to avoid such votes when possible. This is, arguably, an abdication of congressional responsibility, but it is politically savvy nonetheless.

The dilemma, however, is that deference now may make it harder to restrict other, more consequential, uses of force later. The Hill may find it tolerable, if distasteful, to acquiesce when Trump launches pinprick strikes against Bashar al-Assad or takes the fight to some new offshoot of ISIS.

But what if the administration had decided to undertake a more significant air campaign against the Assad regime, one that risked Russian casualties and held a higher danger of unwanted escalation? What if this or a future administration decides that a preventive attack on North Korea’s nuclear and missile facilities is, regrettably, necessary?

Having an executive that is only loosely constrained on matters involving the use of force may make sense, pragmatically and politically, in the context of a low-grade, continuing war on terrorism. But there is some danger that a pattern of acquiescence in cases where the stakes seem relatively low may make it harder to wrest back meaningful congressional authority in cases where the stakes are far higher.


Hal Brands
Hal Brands is the Henry A. Kissinger distinguished professor at the Henry A. Kissinger Center for Global Affairs at Johns Hopkins University’s School of Advanced International Studies. -- Ed.

(Bloomberg)