The role of Congress in the conduct of foreign policy has become nearly the opposite of what the founders of this country intended. The architects of the Constitution placed the day-to-day conduct of diplomacy in the hands of the executive branch. Indeed, the need to have the federal government deal with foreign affairs more effectively than it had under the Articles of Confederation was a key reason why the Constitution established a presidency with significant, independent powers.

At the same time, the founders wanted Congress to play a major role in the most crucial aspects of foreign affairs. Thus, all treaties had to receive approval by a two-thirds vote of the Senate. Even more graphic evidence of original intent was the provision regarding the war power. When it came to making the momentous decision about whether to take the republic to war, the Constitution gave Congress, not the president, that authority.

What we have today is a perverse mirror image of that system. Presidents have usurped—and Congress has abdicated—the war power, yet Congress has become more involved in everyday diplomacy.

The last time that Congress declared war, or was even asked to do so, was immediately following the Japanese attack on Pearl Harbor—more than seven decades ago. Yet the United States has fought a record number of armed conflicts, including some very large-scale wars, during that same period. In some cases, such as preludes to the wars in Vietnam, the Persian Gulf, and Iraq, presidents sought vague congressional resolutions that essentially gave the executive a blank check to conduct policy however he wished. In other cases, such as the Korean “police action” and the Balkan interventions in the 1990s, presidents acted without even the fig leaf of perfunctory congressional approval.

With the recent Syrian crisis, President Barack Obama tried both approaches. Initially, he insisted that he had the power to launch missile strikes against Syria without any congressional authorization. When he received surprising push back from Congress, and when numerous opinion polls showed that the American public overwhelmingly opposed going to war without congressional approval, the president beat a tactical retreat and asked Congress for a typical blank-check resolution. He still emphasized, however, that he was seeking legislative approval merely as a matter of courtesy, not that it was a constitutional requirement. Russia’s diplomatic initiative at the UN at least temporarily short-circuited what might have been a refreshing reassertion of the congressional war power.

Even as Congress became (at least until the Syria dispute) little more than a cipher regarding decisions about war and peace, it became increasingly active on measures that should properly be left to the executive branch. Three recent examples highlight that growing tendency to meddle in the day-to-day conduct of foreign affairs.

One was a Senate resolution passed in the summer of 2013 regarding the highly sensitive territorial disputes in the South China and East China seas between China and neighboring states. Several of the “resolved” clauses in the resolution exhibited unsubtle criticism of and hostility toward China.

Not surprisingly, the Chinese government reacted angrily to the passage (by an overwhelming margin) of that resolution. Chinese suspicions have grown over the past four or five years that the United States is injecting itself into the murky, emotional territorial disputes. The last thing the U.S. Senate needed to do was become directly involved (especially in such a biased fashion) and confirm that Washington intends to undermine China’s claims and interests. This set of issues was already a diplomatic mine field, and the Senate’s action increased the likelihood of a detonation.

A second example of congressional meddling involves the sensitive matter of U.S. arms sales to Taiwan. The Obama administration, even more than its predecessors, has sought to pursue a “Goldilocks” strategy regarding the issue—selling just enough modern weapons to satisfy the Taiwanese government without enraging Beijing. That balancing act is inherently delicate and difficult, but recent congressional actions make it more so.

Pressure (especially from the Republican-controlled House of Representatives) is mounting on the Obama administration to sell Taiwan ever more advanced weaponry. House members inserted an amendment in the 2013 National Defense Authorization Act urging President Obama to sell Taipei advanced (C and D) models of the F‑16 fighter—a decision that would cross one of China’s bright red lines of unacceptable U.S. conduct. Reports also circulated in Taiwan that a senior Republican, Senator James Inhofe of Oklahoma, assured Taiwanese officials during a visit to the island earlier this year that the United States would approve the sale of Apache attack helicopters in 2014 and Patriot missiles in 2015.

Beijing’s reaction to sales of the Apaches or Patriots would be anything but mild. Chinese officials regard those systems with only a little less hostility than they do the sale of advanced F‑16’s. The Taiwan arms sale issue is sensitive enough without this kind of congressional meddling.

The third, and potentially the most unhelpful and dangerous case of congressional interference involves economic sanctions against Iran. There are now signs of serious negotiations between Tehran and the United States and other major powers regarding Iran’s nuclear program. Although it is uncertain how these latest initiatives will turn out, the signs are at least cautiously encouraging. A breakthrough on the nuclear issue could even lead gradually to the normalization of ties between Tehran and Washington, which would help dampen an especially dangerous flashpoint in international affairs.

One would hope that Congress would let the executive branch conduct this delicate diplomacy with a minimum of interference. Instead, congressional hawks seize every opportunity to push hostile, uncompromising measures that threaten to torpedo negotiations. The Obama administration has urged Congress to hold off on imposing new sanctions. Instead, as soon as the latest round of talks in Geneva faltered over the weekend, Robert Menendez, (D‑NJ), chairman of the Senate Foreign Relations Committee immediately said that the upper house would “move forward” on a bill to cut Iranian oil exports even further. That bill has already passed the House of Representatives. Senator Menendez also stated that any agreement with Iran must include an Iranian commitment to halt all enrichment of uranium—the most extreme, uncompromising position that such ultra hawks as Senators John McCain and Lindsey Graham have long embraced.

This is the worst sort of attempted congressional micromanagement of foreign affairs. The Iranian negotiations are at an especially sensitive point, and such interference could sabotage a potential breakthrough to foster peace in the most volatile region of the world. The executive branch needs to have wide latitude to pursue its diplomacy.

Instead of such unhelpful, if not malicious, interference, Menendez and other members of Congress should concentrate on restoring the badly eroded congressional war power. The decision between war and peace is an exceptionally important responsibility that the Constitution vests in the legislative branch. It is alarming to see that legitimate power wither while members of Congress instead meddle in situations where the Constitution wisely gave the executive branch primary responsibility.