Senior White House officials blocked the Navy from conducting needed freedom of navigation operations in the South China Sea amid growing concerns that China is militarizing newly reclaimed islands, according to the Pentagon's Defense Policy Board.

A working paper produced in September 2015 by John Hamre, the policy board chairman, called for an immediate resumption of Navy warship passages to prevent China from taking over the strategic Southeast Asian waterway.

The internal document was disclosed Monday by WikiLeaks as part of its latest batch of hacked emails from the account of John Podesta, campaign chairman for Democratic presidential nominee Hillary Clinton. The Obama administration has accused "Russia’s senior-most officials" of hacking and leaking the emails posted to WikiLeaks and other sites in order to influence the 2016 election.

The document was labeled "Chairman's Working Notes of the Defense Policy Board – Chinese Island-Building in the South China Sea." It was sent to Jake Sullivan, the Clinton campaign's senior policy adviser, by Stuart Eizenstat, a Defense Policy Board member who was advising the campaign on internal Pentagon deliberations.

In an email accompanying the notes, Eizenstat said he was providing a summary of the board's recommendations after a two-day meeting. Eizenstat, a Washington lawyer, said he was sharing the board's discussion of the South China Sea with the campaign because of the visit to Washington by Chinese leader Xi Jinping at that time, and because "Hillary may be asked to address this question."

"There was a recognition that the Chinese will eventually militarize the ‘islands' they are building ou[t] of rock and coral, and there is little the US can do to stop that," he stated in the September 25, 2015 email.

Eizenstat said the board's main recommendation was for the Obama administration to use a combination of diplomatic, military, economic, and communications strategies to prevent Beijing from taking control of the South China Sea

"The U.S. Navy should launch freedom of navigation operations as soon as possible, and before China fully militarizes the ‘islands', to establish the principle that we consider this to be international waters," Eizenstat said. "We were told that there is a broad consensus to do so, but it is being held-up at the highest levels of the White House."

The policy board memo also recommended that China be prevented from deploying military forces on the disputed islands.

"The U.S. government should outline to Chinese government the responses that will have to come if China militarizes the islands," the Hamre memo says. "We must communicate that we know China won't reverse its island-building activities, but that militarizing the islands constitutes as step that will trigger objective and serious U.S. responses."

No details were disclosed on who within the White House was holding up the operations.

According to the memo, Chinese island-building and military activities in the sea "represent a deep, systematic and strategic development, not a tactical response or passing phenomenon."

"China has a strategic plan and an operational campaign," the memo says. "China plans to create ‘facts on the ground' that establish their strategic interests in controlling the South China Sea for political and economic benefit."

The Chinese activities are a "strategic political move designed to establish Chinese dominance and marginalize U.S. influence in the region," the memo states.

The Obama administration halted freedom of navigation operations in the South China Sea between 2012 and October 2015, then resumed them under pressure from Congress. Such operations involve sailing within 12 miles of disputed islands. They are allowed under international law as a means to declare open seas free to all ships.

Defense officials said Obama administration officials opposed the ship passages as too provocative and disruptive of U.S.-China relations.

Hamre, in an email, said he has not spoken to Eizenstat about the two-page summary. He said the document was written to lay out "talking points that we use for our conversation with the Secretary."

The Navy's close-in warship passage operations resumed just over a month after the internal Pentagon report was produced. On October 27, 2015, the warship USS Lassen sailed within 12 miles of a disputed feature in the Spratly Islands. A second naval passage took place in January near the Paracel Islands.

However, the freedom of navigation operations were again halted from January until last week, when the guided missile destroyer USS Decatur sailed near one of the Parcels.

Hamre, the board chairman, warned in the working paper that delays in the Navy warship passages had undermined America's standing and that Chinese militarization of the new islands would pose dangers for resumed warship passages.

"A delay on ‘freedom of navigation' operation is hurting U.S. standing in the region," Hamre stated. "It will become more difficult and confrontational to launch freedom of navigation operations AFTER China has militarized the newly-built islands."

"We should launch freedom of navigation operations as soon as practicable and sustain them on an ongoing basis," Hamre added.

The Pentagon has said China has reclaimed some 3,200 acres of islands in the Spratlys and Paracels on features that are claimed by the Philippines, Vietnam, and other states in the region.

After quietly building up the new islands, China has begun deploying military forces there, including anti-ship and air-defense missiles and temporary deployments of fighter jets.

"This is not a crisis, but it is a long term problem that will require a policy consensus that transcends administration's for years to come," Hamre said. "The problem is not island-building, but rather unilateral actions by China to redefine political conditions that are designed to marginalize U.S. influence in the region."

Hamre said the United States needed a strategy to deal with a "surging China" that is not limited to the island-building problem. In the edited talking points, "surging" was crossed out and "aggressive" was handwritten in its place.

"The administration needs to set the stage for the next administration to engage China, but confront China's unilateral actions to intimidate neighbors as counterproductive and out of touch with the 21st Century," he said.

The talking points appear to have been the basis for Pentagon policy and included several themes emphasized in public remarks since 2015 by Defense Secretary Ash Carter, who has called for China to observe international norms of behavior in the South China Sea and to support the Philippines in its dispute with China.

A program to provide $400 million in aid to regional states should be increased, the memo said.

The memo also urged ratification of the controversial United Nations Convention on the Law of the Sea.

National Security Council spokeswoman Emily Horne declined to comment on the leaked email or internal, interagency discussions.

"As President Obama has stated, the United States will fly, sail, and operate wherever international law allows," Horne said. "That is true in the South China Sea as in other places around the globe."

Eizenstat, the policy board member, stated in his email that the U.S. government "should speak with one voice about the fact that Chinese activity contravenes rules-based international norms."

"They are building this artificial ‘islands' to then stake out a claim to jurisdiction in the seas abutting them," he said.

Eizenstat did not return an email seeking comment.