The largely symbolic move comes after the International Court of Justice ordered the United States to ease some sanctions on Iran.
WASHINGTON — Secretary of State Mike Pompeo announced on Wednesday that the United States was pulling out of a six-decade-old treaty with Iran that had provided a basis for normalizing relations between the two countries, including diplomatic and economic exchanges.
The largely symbolic move came hours after the International Court of Justice ordered the United States to ease some of its recently imposed sanctions against Iran, including those related to the supply of humanitarian goods and civil aviation safety.
The court ruling was essentially an injunction related to a lawsuit filed by Iran that challenged a new round of American economic sanctions that President Trump had imposed after he withdrew from a nuclear agreement between Tehran and world powers in May. Iran is arguing in the lawsuit that the sanctions violated the decades-old treaty.
Mr. Pompeo cast the lawsuit as an attempt to interfere with the sovereign rights of the United States.
He said that drove the Trump administration’s decision to withdraw from the Treaty of Amity, Economic Relations and Consular Rights, which was signed in 1955. “The Iranians have been ignoring it for an awfully long time,” he said.
“Iran is abusing the I. C. J. for political and propaganda purposes,” Mr. Pompeo said, adding that the court’s decision was outside its jurisdiction and that Iran’s appeals were “without merit.”
However, he said that the United States would continue to try to deliver humanitarian aid to the Iranian people, and that existing exceptions to the economic sanctions would remain in effect.
The decision by the court, at The Hague, came at a critical moment in the Trump administration’s effort to isolate Iran.
In early November, the United States is expected to impose a broad series of additional sanctions against Tehran that will threaten to cut off companies around the world that also do business with Iran.
But the administration is also thinking more broadly about how to contain all commerce with Tehran, only days after President Hassan Rouhani of Iran said he would consider re-entering negotiations with the United States only if Mr. Trump first recommitted to the nuclear deal that was struck in 2015.
The treaty Mr. Pompeo is leaving bears little relevance to the current relationship between Washington and Tehran. It was negotiated just after the C. I. A. helped stage a coup in Iran that Iranians still cite today as a gross violation of the country’s sovereignty.
The treaty sets up commercial relationships, tax structures and access to each nation’s courts. None of that has applied since the 1979 Islamic revolution.
But in rejecting it, Mr. Pompeo is also rejecting any return to normalized relations with Iran, which was the overall, long-term objective of the 2015 nuclear accord, beyond getting 97 percent of the country’s nuclear material moved outside its borders.
In announcing the scuttling of the treaty, Mr. Pompeo underscored a larger strategy by the United States to confront Iran across the Middle East, emphasizing what he said were hostile Iranian actions.
On Friday, he announced the United States was evacuating all diplomats, security guards and other employees from its consulate in Basra, Iraq, because of several recent rocket attacks there by Iranian-backed militias. Those rockets landed on the perimeter of the airfield where the consulate is and injured no one.
Senior State Department officials had debated for more than a year whether to shut down the consulate to save money. Mr. Pompeo said on Wednesday that intelligence indicating that Iran was behind attacks was “solid.”
“We can see the hand of the ayatollah and his henchmen,” Mr. Pompeo said, referring to Iran’s supreme leader, Ayatollah Ali Khamenei.
