Preserving and promoting the US’ legal obligation to provide for Taiwan’s self-defense needs is a tricky business. Every sale — particularly the biggest — must wind its way through a complex maze of US and Taiwanese party politics, bureaucracies, legislators and media.

Often, the US and Taiwan are not aligned internally, let alone with one another.

The People’s Republic of China only complicates the task. Its influence, coupled with the lack of high-level contact between Washington and Taipei, necessitate a sort of signal-sending that leaves even the fully initiated sometimes grasping for meaning.

So what are Taiwan’s supporters in Washington to make of Taipei’s current debate over the value of its six-year-old request for 66 new F-16C/Ds? It is hard to know.

Taiwan’s previously expressed interest in these aircraft is well founded.

First, it needs both the upgrades of its F-16A/Bs (already approved by the White House) and the new F-16C/Ds. The C/Ds would replace Taiwan’s old F-5s, at least half of which are no longer operational. The C/Ds are unquestionably superior to upgraded A/Bs, and not just because the A/B airframes are 20 years older. The new aircraft have more powerful engines, which means more ordinance, faster speeds and longer range. Upgrading the A/Bs is a must, but it cannot stand alone. Taiwan needs new aircraft with additional capabilities to maintain a credible deterrent.

Second, without new aircraft, Taiwan faces a gap between 2017 and 2021 when the F-16A/Bs are taken out service for the upgrades. Only delivery of the new C/Ds can fill that gap.

Third, the odds that the US’ fifth-generation F-35 Joint Strike Fighter will be sold to Taiwan any time in the near future (less than 15 years) is virtually nil.

Leaks from the Defense Intelligence Agency’s report last year on Taiwan’s air power requirements — which indicated a need for short takeoff and vertical landing (STOVL) capability — probably helped divert the public debate into this unproductive speculation. The agency’s finding in this regard is open to dispute, not least because STOVL-capable fighters are so rare today. The F-35B is the only one in or near production.

Fourth, the F-35s, even if available to Taiwan, would cost many times more than new F-16s and could not arrive in time to fill the gap. Essentially, Taiwan has neither the time nor the money to acquire F-35s.

Because supporters know these facts, and presumably the parties contributing to the debate in Taipei know them, the danger is that Washington will interpret uncertainty about the value of new F-16C/Ds as a signal that Taiwan does not want new planes.

The mixed signals from Taipei are particularly troublesome right now.

Momentum for the sale of 66 new F-16C/Ds has built on Capitol Hill over the past year. Last year, Congress produced two letters urging the sale: one from the Senate with 45 signatures and another from 181 representatives. Two high-level administration nominations were held up over the matter, including that of the deputy secretary of state and the new assistant secretary of defense for Asian and Pacific affairs. Just last month, the House of Representatives amended the annual defense authorization bill to mandate the sale. A similar effort in the Senate will likely succeed when taken up later this year.

However, the effort may falter if mixed signals from Taiwan inadvertently quash congressional support for the sale.

What is necessary is a new urgent effort from Taiwan — including from President Ma Ying-jeou (馬英九) — that makes it absolutely clear that Taipei’s interest in the F-16C/Ds has not flagged since the January elections.

The Ma government’s reluctance to challenge US President Barack Obama’s administration is understandable. In a sense, it is hostage to Obama’s good graces. The administration has not been all bad for Taiwan. It approved the remainder of former US president George W. Bush-era arms sale commitments to Taiwan, including Black Hawk helicopters. It approved upgrades to Taiwan’s F-16A/Bs, something it did in lieu of selling new aircraft, but which was necessary nevertheless. It has also been forthcoming in terms of regular quasi-diplomatic consultations, which the Taiwanese have found comforting.

However, reiterating interest in the F-16s is hardly challenging the Obama administration. Taiwan has expressed that interest previously. Moreover, the Obama administration itself in April explicitly and publicly acknowledged the need for a “near-term course of action” on how to address Taiwan’s fighter gap. There is no other viable option but to make good on the planes Taiwan has for so long said it wants.

No one is asking Taiwan to lobby for legislation forcing Obama’s hand. What is needed are clear signals that the F-16C/D remains critical to the Ma government’s interest in addressing what the Obama administration itself has called a “growing military threat to Taiwan.”

Having cleared the air, Taiwan can leave the fight over how to meet its defense needs to the normal give and take in Washington.

-Walter Lohman is director of the Asian Studies Center at the Heritage Foundation.