"We are not going to be able to continue contributing to the budget," State Department spokeswoman Victoria Nuland said. "Palestinian membership as a state in UNESCO triggers longstanding legislative restrictions which will compel the United States to refrain from making contributions to UNESCO."
Washington is required by law to cut off funding to any U.N. agency if the Palestinian Liberation Organization is granted membership in any group at the international body.
The United Nations Educational, Scientific and Cultural Organization voted 107-14 with 52 abstentions on Monday granting Palestinians full membership in the organization. The U.S. voted against the nomination. Eighty-one votes of the 173 UNESCO members were needed for full membership to be approved.
"Long Live Palestine!" one delegate reportedly shouted in French at the meeting.
The U.S. funds about 22 percent of UNESCO's budget, or roughly $80 million annually. Nuland said the $60 million was scheduled to be sent in November.
"We obviously have to comply with U.S. law, to comply with U.S. restrictions. That said, we will have a conversation with Congress on moving forward," she said.
Nuland said that if the U.S. ends up in arrears it could challenge U.S. membership status.
The U.S. rejoined UNESCO in 2002, after having left the organization 19 years earlier.
An aide to House Foreign Affairs Committee Chairwoman Ileana Ros-Lehtinen said the congresswoman supports full enforcement of the law, without exception.
Ros-Lehtinen, R-Fla., has also introduced legislation that would withhold U.S. contributions from any U.N. agency or program that "upgrades" the status of the Palestinian observer mission at the U.N, whether full membership or not.
Ros-Lehtinen has previously argued efforts at de facto recognition of a Palestinian state is an attempt to evade a negotiated settlement with Israel.
Former U.S. Ambassador to the U.N. John Bolton said the U.N. vote signals weakness in U.S. diplomacy, particularly since some of the United States' closest allies voted against U.S. wishes.
"So ineffective was Obama administration diplomacy, that France voted in favor of Palestinian membership, and Britain and Japan abstained. U.S. statutes, dating from 1990, now require a full cutoff of U.S. funding, which Congress should insist occur immediately. Should the administration seek changes in the applicable statutory provisions that would eliminate or weaken the funding cutoff, Congress should reject them," Bolton said.
"UNESCO has made its decision: it prefers Palestinian membership to American participation. Now let the rest of the U.N. specialized agencies make their choice," he added.
Nuland said that the U.S. doesn't think it is "helpful" that the Palestinians sought membership with UNESCO while the "Quartet" of nations working on Mideast peace tries to get the Israelis and Palestinians back to the negotiating table to create a two-state solution.
"We considered that this was, as I say, regrettable, premature, and undermined the process of getting where we want to go," she said. "It creates tensions when all of us should be concerning our efforts to get the parties back to the table."
Israel's ambassador to UNESCO Nimrod Barkan told Reuters that the vote is a tragedy.
"UNESCO deals in science, not science fiction," he reportedly said. "They forced on UNESCO a political subject out of its competence."