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The Senate’s treaty oversight has atrophied just as it’s needed most

Unable to unify behind or against foreign deals, the Senate has ceded power to the president

President Donald Trump announces withdrawal from the Iran nuclear agreement in 2018.
President Donald Trump announces withdrawal from the Iran nuclear agreement in 2018. (Chip Somodevilla/Getty Images)

ANALYSIS – Pressing national security concerns stemming from Russia’s invasion of Ukraine and Iran’s nuclear development are highlighting anew just how much the Senate has allowed its capacity to oversee treaties and international agreements to deteriorate.

In large part due to political polarization, the Senate often cannot muster the two-thirds support needed to approve major treaties. With Congress divided, presidents have increasingly skirted the two-thirds vote by entering international agreements that don’t require it. That has contributed to the concentration of foreign policy power in the executive branch.

Meanwhile, presidents, particularly Republican ones, have moved to unilaterally withdraw from ratified treaties, and Congress has not objected, further weakening its oversight power.

“I frankly think a president should not be able to withdraw from any treaty without congressional approval,” said Sen. Tim Kaine, D-Va., in a press call last month on his push for a vote on a resolution he sponsored that would prevent any president from withdrawing from the NATO treaty without first getting congressional backing. “Because treaties require the Senate to get into them, I don’t think you should get out of them without congressional involvement.”

Kaine’s measure, which the Senate Foreign Relations Committee advanced in late March by a 21-1 vote, would require a two-thirds majority vote in the Senate or an act of Congress before any president can withdraw from the Western military alliance.

The impetus for the committee vote on Kaine’s resolution, which has been around in one form or another since 2018, was lawmakers’ desire to send a signal to Europe and Russia amidst the war in Ukraine.

“The reason this bill is frankly getting a full hearing and a recorded vote is because we’re realizing the importance of NATO in a way we haven’t, frankly, in my lifetime,” said Kaine.

Kaine added that the Biden administration supports his resolution as do ambassadors from both NATO and non-NATO member countries.

“They believe it will send a very powerful message about the Article 1 branch support of NATO,” said Kaine, referencing Congress’ place in the Constitution.

But the other, much less-publicly acknowledged reason why the Senate is now taking steps to protect the NATO treaty are worries about what a future president might do to undermine the alliance.

Last week at a Heritage Foundation event, former President Donald Trump appeared to confirm reports that he had called into question at a NATO summit in Brussels in 2018 whether he would honor the U.S. commitment to come to the defense of alliance members if he felt they weren’t spending enough on their own security.

According to Trump’s recollection, another NATO member country’s leader asked him if he would defend it from Russia if Trump felt the leader’s country wasn’t spending enough on its own defense. “I said that’s exactly what it means,” Trump said, justifying his threat as a negotiating tactic to convince allies to spend more on their militaries.

Whipsaw effect

Trump’s attitude toward that treaty obligation, combined with his failure to respect other international deals struck by previous presidents, undermined U.S. credibility abroad, according to interviews with multiple former U.S. diplomats and national security law specialists.

Trump, for instance, withdrew the U.S. from involvement in the Paris Agreement to address global climate change that his predecessor, President Barack Obama, had negotiated in 2016. President Joe Biden has since rejoined the Paris climate agreement.

U.S. participation in the multinational accord to constrain Iran’s nuclear program has gone through similar about-faces with Trump in 2018 pulling the United States out of the Obama-negotiated pact. Though the Biden administration is searching for a way back into the accord, 49 out of 50 GOP senators have essentially promised that Washington will exit any renewed Iran deal just as soon as there is a Republican back in the White House.

Republicans are also raising anew their demand that any such atomic agreement be treated as a treaty and submitted to the Senate for approval.

“I think it’s really not at its core a separation of powers issue. It’s really about the desire to kill that [Iran deal],” said David Koplow, a national security law professor at Georgetown University, of Republicans’ motives. “In a less polarized time, there could be an informed, reasonable debate about which format to use and there could be pros and cons to each.”

Democrats see GOP protestations over the legal form that an Iran nuclear agreement takes as hypocritical considering Republican acquiescence to Trump’s flouting of congressional oversight on national security topics.

For example, Democrats objected to Trump unilaterally withdrawing from arms control and nonproliferation treaties with Russia. Republicans didn’t share their concerns and cheered on the Trump administration’s actions, including the withdrawal — without meeting congressionally-established legal requirements — from the Open Skies Treaty, which permitted surveillance overflights of Russian territory.

The lack of protest was notable because a year earlier, Republicans had joined with Democrats in including a provision in the fiscal 2020 National Defense Authorization Act that required notifications to Congress and consultations with allies take place before the United States could pull out of the treaty.

A constitutional debate

The Constitution’s requirement of a two-thirds vote for Senate treaty approval is higher than the bar facing legislation, which in theory only needs simple majorities from both chambers.

And so it is notable that the Constitution is silent on the process for withdrawing from treaties. In the only real test case in 1978, in which lawmakers challenged President Jimmy Carter’s decision to withdraw from a defense treaty with Taiwan, the Supreme Court said that Congress and the president needed to work out the details themselves.

The balance of power remains ambiguous.

“It’s a gray area because the Congress wants to leave it a gray area,” said Melvyn Levitsky, a professor of international policy and practice at the University of Michigan and a former career diplomat who served as ambassador to Brazil and Bulgaria. “They want to insist on their right but not to test it when the president seems to violate it.”

Republicans, for example, are insisting it’s reasonable to demand that Biden negotiate a return to the Iran nuclear agreement as a treaty, even as they threaten that a future president could withdraw from it without a Senate vote.

Meanwhile, they are also signaling their willingness to defend treaties they view as essential to U.S. interests.

“NATO is a critical alliance, and no one, especially Putin, should be under any illusion that America’s commitment to the North Atlantic Treaty is fleeting,” Sen. Marco Rubio, R-Fla., Kaine’s principal GOP co-sponsor on the NATO treaty resolution, said in a statement. “By contrast, everyone should realize that non-treaty agreements, especially ones that empower our enemies in Iran, are very likely to vanish with the election of a new president.”

Modern presidents negotiate 95 percent of their international agreements as executive agreements rather than as treaties, according to a 2015 research paper by Clemson University political scientist Jeffrey Peake that examined deals negotiated by the George W. Bush and Obama administrations. Peake argued that the shift toward executive agreements violated “the norms developed during the 20th century that most significant agreements will be completed as treaties or with some direct input from Congress.”

At the same time, Peake suggested he understood the shift, given that the majority of the treaties transmitted to the Senate for approval languished without committee or floor votes amid deep party polarization.

“What is the president to do when American political institutions routinely fail to finalize international commitments? Should the president do nothing and thus limit the ability of the United States to conduct its diplomacy,” Peake asked.

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