Finance ministers from the 15 United Nations Security Council nations will adopt a plan today aimed at disrupting outside revenue that the Islamic State extremist group gets from oil and antiquities sales, ransom payments and other criminal activities.
The United States and Russia have joined forces to draft the resolution to strengthen sanctions against those who do business with terrorist groups, chiefly the Islamic State.
That agreement hints at the possibility of greater cooperation to end the civil war in Syria.
The mammoth 28-page draft resolution, which is expected to be adopted today at a meeting led by the United States Treasury secretary, Jacob Lew, repackages sanctions that have been in place for more than a dozen years, but are often flouted.
The draft calls on countries to describe what steps they are taking to prevent terrorist organisations from making money, including interdicting oil sales. It also aims to prevent the groups from using international banks, and bolsters monitoring efforts by the United Nations.
The effects may be limited: The Islamic State draws a large share of its revenues from ''taxes'' imposed on the people who live in its territories.
Still, diplomats said, the resolution was an important measure of fledgling cooperation between top American and Russian officials to negotiate a political accord on the Syrian conflict.
They have both increasingly focused on what they agree on - combating the threat of the Islamic State - and deferred the question that they disagree on - what becomes of Syria's president, Bashar al-Assad.
The next test of that cooperation will come when diplomats from more than a dozen countries are to gather in New York with the aim of getting the Syrian government and opposition groups to agree to a cease-fire and a transitional government in January.
Consensus around such a sanctions resolution would be a significant breakthrough.
The American ambassador to the United Nations, Samantha Power, described that prospect as ''the first, very high profile way that the Security Council would show its unity around the importance of achieving a political settlement'' and routing the Islamic State.
What vexes the United States and Russia is not just their own differences about the future of Syria, but the rival agendas of their allies in the region, namely Saudi Arabia, Turkey and Iran.
Three main differences remain between Russia and the United States. Washington has declined to cooperate with Moscow on military strikes against the Islamic State. Russia and the United States do not agree on which Syrian opposition groups should be part of a cease-fire and which should be deemed terrorist. And publicly at least, the two world powers remain at odds over whether. Assad should be allowed to take part in any future elections.
Secretary of State John Kerry made it clear on Tuesday that the United States was not ''seeking regime change in Syria,'' while also insisting that. Assad could not lead what he called ''the future Syria.''
On Wednesday, speaking to reporters at the United Nations, the secretary general, Ban Ki-moon, said that he hoped the diplomatic efforts to end the Syrian conflict would not be ''dependent on the fate of one man'',. Assad.
The focus on the Islamic State was underscored on Wednesday afternoon, when at a Council briefing led by the United States, a Yazidi woman from Iraq, Nadia Murad Basa Tahee, spoke of her captivity and called for the world to recognize that the Yazidis had been subjected to a genocide.
''The Islamic State has made Yazidi women into flesh to be trafficked in,'' she said.
There are already legally binding measures against several banned terrorist organizations, including Al Qaeda and the Islamic State, that prohibit making donations, trading in oil and antiquities and making ransom payments.
The new draft resolution ''expresses increasing concern about the lack of implementation'' of several of these measures - something that Russian officials have complained about - and it calls on countries to report to the Council on what steps they are taking to enforce them.