NEW YORK – An outright American withdrawal from the Iran nuclear deal would isolate the United States – not Iran, a top US senator on foreign policy said on Sunday.

Speaking at the annual Jerusalem Post Conference in New York, Maryland’s Democratic Senator Ben Cardin, who is a senior member of the Foreign Relations Committee, warned against a hasty exit two weeks ahead of a deadline set by US President Donald Trump on European powers to propose “fixes” to the 2015 accord.

Without “substantially” improving upon some of its most controversial provisions, according to administration officials, Trump will reimpose harsh nuclear sanctions on Tehran – effecting pulling the US out of the deal.

“I am for making sure Iran never has a nuclear weapon, but I don’t want to see us isolate the United States from our allies,” Cardin told the conference. “We need to work with the international community to isolate Iran.”

France, Britain and Germany said in a joint statement on Sunday that there are “important elements that the deal does not cover,” and have agreed to work toward a “new deal” that might address them – including Iran’s ballistic missile work, its regional military posture, and its long-term nuclear activity. But they also underscored the importance of keeping the existing deal, which they believe adequately addresses Tehran’s nuclear work in the short-term.

By withdrawing too quickly, without a comprehensive plan for the day after, “we isolate the United States rather than isolate Iran,” Cardin said. He said the Senate would support “much stronger actions” on Iran’s non-nuclear activity, not covered by the 2015 deal negotiated under the Obama administration amongst six world powers and Iran.

Cardin was the top Democrat on the Senate Foreign Relations Committee when Congress passed oversight legislation on the Iran nuclear deal. He disapproved of the ultimate agreement once it came to a vote in the chamber in 2015.

The senator also said that the US should maintain a presence in Syria to ensure that Iran does not fill any vacuum a withdrawal of US troops might create, amid talk within the Trump administration of a complete withdrawal of forces.

“The United States needs to be engaged on how this civil war ends in Syria,” he said, expressing hope that embattled Syrian President Bashar Assad ends up in The Hague over his war crimes. “I don’t think we’ve been effective.”

He said he supported Trump’s decision to move the US Embassy in Israel from Tel Aviv to Jerusalem, although he questioned the strategic approach: “The matter in which the president handled it, in my view, was a missed opportunity. But Israel’s capital is Jerusalem, and we’ve all recognized that and will continue to recognize that,” he said. “Every country determines its own capital – what’s the big news here?”

The Democrat has been a strong supporter of legislation to combat the boycott, divestment and sanctions movement in the US and abroad, a movement that has found some support within his party’s base. He acknowledged this political reality but denied that it has had any institutional effect, noting “unanimous support” for recent anti-BDS legislation.

“I haven’t seen that division in our political system,” he said, “and it must remain that way.”