In a May 1 letter to Congress citing the current ceasefire, the Trump administration has declared hostilities with Iran terminated. Under the War Powers Resolution, which dates from the Vietnam War, a president has sixty days after the start of hostilities before congressional authorization must be secured.
The United States and Israel launched joint attacks on Iran on Feb. 28, but under the law the clock formally started ticking on March 2, when Trump officially notified Congress.
The U.S. continues a naval blockade of Iran, which under international law is an act of war.
The 1973 War Powers Resolution passed over the veto of weakening President Richard Nixon, entangled in the Watergate scandals. While the law stipulates a president may use military force overseas for 60 days without congressional authorization, an additional 30 days is available for the conduct of withdrawal. Under this statute, Congress also can order immediate withdrawal of forces.
From the beginning of the United States, there has been tension between the executive branch and legislature over foreign policy. President Thomas Jefferson took independent initiative to protect American ships from armed attack but informed Congress.
President Abraham Lincoln provides the most dramatic example of operating independently of Congress. He provoked the Confederacy into firing the first shots, then delayed convening Congress, and often acted without consulting legislators.
Lincoln argued the constitution was never intended to facilitate national destruction. He insisted the conflict was a domestic matter.
President Franklin Roosevelt, while a reformer domestically, was relatively cautious in foreign affairs until World War II. Japan’s attack on Pearl Harbor ended powerful American isolationism.
His successor President Harry Truman significantly strengthened presidential authority regarding war.
In late June 1950, North Korean forces invaded South Korea. The United Nations Security Council — with Soviet representatives absent — voted to repel the attack. Under this authority, and also a resolution of the Organization of American States, Truman committed American forces to the U.N. effort.
Congressional leaders were consulted and concurred that a declaration of war was not necessary. This set a precedent for later executive branch independence in using force, most notably in Vietnam.
The memoirs of Secretary of State Henry Kissinger, who served both Nixon and successor Gerald Ford, describe careful consideration accorded the War Powers Act during those turbulent years, but over time this law faded in influence. The Reagan administration successfully resisted invoking the act in deploying U.S. military forces to the Middle East, bombing Libya and invading Grenada.
President George H.W. Bush proved to be a particularly strong and decisive leader in reasserting executive authority. Operation Just Cause, the U.S. military intervention in Panama, was conducted without advance congressional approval. Bush did provide a report to Congress afterward, noting in passing the War Powers Act.
Underscoring the importance of the Truman precedent, Bush explicitly declared the U.S. was authorized to participate in the First Gulf War under the authority of the United Nations. However, he also secured a resolution of support from Congress,
These precedents eased use of force without congressional authorization. President Bill Clinton did so in the 1999 Kosovo War and Barack Obama in 2011 strikes in Libya. In both cases NATO, and in the latter the U.N., authorized force.
Obama also declared chemical weapons use by Syria intolerable, though when they were used he referred to Congress. Russia’s diplomats resolved that crisis.
Growing congressional pressures may eventually limit President Donald Trump’s overseas adventures, though he vows otherwise. Historically, such tension is inevitable.