The Obama administration blocked a $1 billion arms sale to Taiwan in December that was needed to improve the island's defenses despite approval from the State Department and Pentagon, according to Trump administration officials.

The scuttling of the arms package was a set back for U.S. and Taiwanese efforts to bolster defenses against a growing array of Chinese missiles and other advanced weaponry deployed across the 100-mile Taiwan Strait.

The action coincided with a controversial pre-inaugural phone call Dec. 2 between then-President-elect Trump and Taiwan's President Tsai Ing-wen.

It could not be learned if the arms package, which was ready to be announced publicly in December was derailed by the Obama administration because of the phone call.

The new Trump administration is now preparing to provide more and better defensive arms to Taiwan, said administration officials familiar with internal discussions of the arms sale.

The new arms package, however, is not expected to be made public until after Trump meets with Chinese leader Xi Jinping next month. White House officials said the meeting is set for early April at Trump's Mar-a-Lago estate in South Florida.

Secretary of State Rex Tillerson also will visit China later this month.

Taiwan is expected to be a major topic of discussion for both the summit and Tillerson's visit.

"There's a process for these things that's being followed," a White House official said of the arms package. "The Trump administration takes America's commitment to Taiwan's security very seriously."

Other officials said the arms package was set for release to Taiwan and formal notification to Congress in December. But National Security Council staff officials blocked it, setting back the process of supporting Taiwan with defensive arms considerably.

The approximately $1 billion included parts and equipment needed for the Taiwan military's ongoing modernization of its arsenal of 1980s-era F-16 jet fighters along with additional missiles.

The approved package was held up by Avril D. Haines, the Obama White House deputy national security adviser. Haines did not return an email seeking comment.

Former Obama administration spokesman Ned Price confirmed that the administration held up the arms package. He told the Washington Free Beacon that neither Haines nor others in the Obama White House "unilaterally blocked the package that was under discussions, which was relatively modest."

"In consultation with State and DoD, the Obama administration decided not to move forward with it in the final days of the administration," Price said, adding that one factor was that "we thought it would be a useful package for the next administration to pursue in their time because it was well-calibrated to strike the balance we typically try to achieve consistent with our commitments under the Taiwan Relations Act."

One administration official said the package also included communications, intelligence surveillance, and reconnaissance gear that would bolster the Taiwan military's command and control systems.

This official said one positive aspect of the failure to send the latest arms is that pro-China officials in the U.S. government who oppose helping Taiwan will no longer be able to argue internally that the United States had fulfilled its obligations under the 1979 Taiwan Relations Act with the package. The act requires the United States to provide Taiwan with defensive weapons.

"Now we can start from scratch with a truly useful arms package once the assistant secretaries are in place," the official said, referring to working-level political appointees at the Pentagon and State Department.

State Department spokesman Mark Toner had no immediate comment.

Pentagon spokesman Cmdr. Gary Ross said he does not discuss "pre-decisional matters."

"The objective of our defense engagement with Taiwan is to ensure that Taiwan remains secure, confident, free from coercion and able to engage in a peaceful, productive dialogue to resolve differences in a manner acceptable to people on both sides of the Taiwan Strait," Ross said, noting U.S. arms sales support that goal.

"We strongly believe that our policy has contributed to stability in the Taiwan Strait by providing Taipei with the confidence needed to pursue constructive interactions with Beijing."

The official Taiwan government office in Washington had no comment on the arms package.

Taiwan officials are looking forward to working closely with the Trump administration in upgrading defenses. The Taiwanese are considering the development of indigenous fighter aircraft and submarines and are hoping the United States can provide technology for the arms.

Former State Department official John Tkacik said the failure to release the arms package in December was a mistake.

"It is truly alarming that the White House, in its last month, would ignore a defense transfer recommendation endorsed by both the State and Defense Departments, especially after the incoming president had already signaled his support of a strengthened security relationship with Taiwan," Tkacik said.

Tkacik said it is likely that Obama administration officials in charge of Asia policy, after eight years of giving the Chinese free rein in Asia, were unhappy with Trump's tough posture toward Beijing.

"If the new National Security Council can't move forward afresh with strengthened defense supplies to Taiwan, given State and Pentagon recommendations to do it, I'm afraid the new administration will lose its momentum, like Obama's people did, and simply resign itself to letting Beijing take over in Asia," he assed.

Randall Schriver, a former assistant secretary of state and assistant secretary of defense, said the Trump administration should increase arms transfers to Taiwan.

"China's growing capabilities combined with an intent to put greater pressure on Taiwan should compel us take a serious look at increasing our security assistance to Taiwan including support for its indigenous submarine program and making available a [vertical, short-take off and landing] fighter aircraft," he said.

Rick Fisher, an expert on Asian military affairs, also voiced concern.

"It is extremely disappointing that the Obama administration would not release this final arms sales package before leaving office, but at a deeper level, that it did not exercise the leadership to accelerate this F-16 upgrade package first approved in 2011," said Fisher, senior fellow at International Assessment and Strategy Center.

The delay in upgrading the jets means China has gained six years on deploying advanced fighters jets and next generation short and medium range ballistic missiles that threaten Taiwan.

Fisher warned that China is preparing for a possible invasion of Taiwan in early 2020 and the Trump administration should provide new military capabilities for the island to help deter any Chinese attack.

"We are really up against the wall; if we cannot devise the right package of fifth generation capabilities, be it new F-35 fighters, submarine technologies, new, cheap, long range anti-ship cruise missiles and energy weapons, then we will face the threat of Chinese invasion of Taiwan perhaps as soon as the early 2020s," Fisher said.

Taiwan in January began upgrading its force of 144 F-16s. The jets will be outfitted with active electronically scanned array fire-control radar that analysts say can detect radar-evading stealth aircraft.

New avionics equipment also is being added along with advanced AIM-9X Sidewinder air-to-air missiles.

The last arms package for Taiwan was announced in December 2015 and was worth $1.83 billion. It included two Perry-class Frigates, Javelin anti-tank missiles, TOW anti-tank missiles, and amphibious assault vehicles. Command and control hardware, F-16 gear, Phalanx Close-In Weapons Systems and Stinger surface-to-air missiles were also part of that package.

In December, China's military conducted a show of force with a squadron of jet fighters and a bomber that circled Taiwan Dec. 10.

U.S. EP-3 and RC-135 reconnaissance aircraft shadowed the Chinese jets during the incident, along with a long-range RQ-4 Global Hawk drone aircraft.

The Chinese saber rattling against Taiwan coincided with Trump's phone call with Tsai.

China also protested a provision of the fiscal 2017 defense authorization bill that was signed into law in December. The new law contains language calling on the Pentagon to conduct a program of senior military exchanges with Taiwan.

Current policy has limited military exchanges between U.S. and Taiwanese officers despite a requirement under the Taiwan Relations Act for the United States to defend Taiwan against a Chinese attack.

The phone call between Trump and Tsai in December was the first time an American president had spoken directly to Taiwan's president in decades and prompted protests from Beijing, which views Taiwan as a break away province.

The United States does not accept China's interpretation of the so-called One-China policy and regards the Beijing-Taipei dispute over Taiwan's status as unresolved.

"Interesting how the U.S. sells Taiwan billions of dollars of military equipment but I should not accept a congratulatory call," Trump tweeted Dec. 2.

Trump has taken a hard line against China, mainly over unfair trade and currency practices. After the Dec. 2 call, he also suggested the United States might abandon the One China policy and adopt more favorable Taiwan policies.

However, Trump later reiterated U.S. support for the American interpretation of the One China Policy.