WASHINGTON -- The White House is declining to confirm or deny a report in the Wall Street Journal published on Thursday alleging US President Barack Obama sent Iranian Ayatollah Ali Khamenei a letter suggesting cooperation their fight against Islamic State.But speaking to The Jerusalem Post on Thursday afternoon, National Security Council spokeswoman Bernadette Meehan said that US policy on Iran regarding cooperation in the fight against Islamic State "has been clear.""We are not and will not coordinate militarily with Iran," Meehan said. "We have also been clear that the nuclear negotiation is a separate issue from actions regarding ISIL [Islamic State].” At the same time, she added, "we have been clear that ISIL represents a threat not only to the United States, but also– and most immediately– to the entire region. We believe all countries, regardless of their differences, should work toward the goal of degrading and ultimately destroying ISIL."The clarification came with no clear acknowledgment of a letter. The White House does not always readout the president's "private correspondence," White House Press Secretary Josh Earnest explained."There is a pretty clear interest that Iran has in this fight against ISIL," Earnest told reporters at his daily press briefing, responding to the report. "Because of Iran's relationship with the rest of the world, its difficult for the United States to work closely with Iran on this endeavor."Earnest said its not in Iran's interest to have a terrorist army at its doorstep. Islamic State holds territory in Syria and Iraq, close to Iran's western border.The Obama administration's position on Iranian involvement in the campaign has not changed, Earnest added.The letter, which could not be independently verified by The Jerusalem Post, reportedly suggested cooperation be tied to an agreement between world powers and Iran over its nuclear program.On that conflation, State Department spokeswoman Jen Psaki reminded journalists on Thursday that American diplomats have discussed Islamic State on the sidelines of the nuclear talks for months. But they have also raised concerns with Iranian military actions in Iraq, she said.Negotiations between world powers and Iran are approaching a deadline on November 24, when the parties hope to seal a comprehensive agreement ending concerns over the program.Obama told reporters at the White House on Wednesday that Iran has been presented with a "framework" that would meet its peaceful energy needs.One State Department official declined to comment on "the specifics of those proposals," and whether they have been whittled down to one so close to the deadline."Throughout negotiations, the P5+1 has put forth creative and reasonable proposals that are equitable, enforceable, consistent with our own core objectives, and consistent with Tehran's expressed desire for a viable civilian nuclear program," the official said.