The Obama administration made a tough call this week, choosing to withhold advanced F-16 C/D fighter jets from Taiwan, which appeases China but risks leaving an important ally vulnerable. The U.S. will instead sell an estimated $4.2 billion arms package to Taiwan, including equipment to upgrade the island nation's aging F-16 A/B jets. Feeding ammo to the administratin's critics, The Washington Times reports that a forthcoming Pentagon study is expected to show that Taiwan's air force "urgently needs modernization." However, there are a number of reasons that show the wisdom of withholding the advanced jets from Taiwan. Here are a handful:

China was throwing a fit As Paul Eckert at Reuters reports, China's Foreign Ministry doubled down on its opposition to the sale of F-16s today, advising Washington to "avoid any unnecessary disturbance and damage to bilateral ties." On the domestic front, "an official newspaper warned that 'madmen' on Capitol Hill pushing the F-16 sale were playing with fire and could pay a 'disastrous price' if the Obama administration went ahead with any sale."

U.S. debt was a factor As Bill Gertz at The Washington Times notes "China’s U.S. debt holdings also likely influenced the decision. In February 2010, Chinese military leaders called for punishing the United States for arms sales to Taiwan by calling in some of the $1.1 trillion in China’s Treasury debt holdings."

It's not clear Taiwan needs the jets In an interesting scoop from Paul Mozur and Jenny W. Hsu at The Wall Street Journal, an insider tells them "some in the Taiwan military don’t necessarily want the new F-16 C/Ds."

The person said those officers no longer see the acquisition of the new planes as urgent, particularly given a tight military budget. The person added that many see other weapons systems, such as diesel-electric submarines as more effective deterrents, particularly to China’s rising naval might. If a sale of the F-16 C/Ds were to come on the back of the A/B upgrade package, the person warned, it could cut into Taiwan’s budget in ways that would make it difficult to carry out other important domestic projects.

The F-16s are more offensive than defensive Bill Gertz notes that one assessment of the advanced F-16s showed that the planes "were far more capable than earlier F-16s because of their strike capabilities and could be considered as undermining the U.S. pledge to provide only defensive arms to Taiwan."

Still, there were a number of forces pushing for the sale to happen, and as The Wall Street Journal notes today, the U.S. could still sell the F-16s at a later date, especially as election seasons draws nearer:

As analysts in the U.S. have said time and again, a decision on F-16 A/Bs doesn’t rule out the chance that C/Ds could be sold later. And given that support in both the House of Representatives and Senate has swelled in recent months – Sens. John Cornyn (R-TX) and Robert Menendez (D-NJ) have offered a bill in the Senate calling for a sale of the C/Ds, and U.S. Rep. Ileana Ros-Lehtinen (R-FL) has introduced a bill calling for President Obama to accept a Taiwan letter of request for the C/Ds –  it seems the fat lady has not yet sung on the newer jets.

With U.S. elections drawing nearer, the number of jobs at stake on the F-16 production line–though not overwhelming–might represent the sort of symbolic move that President Obama can’t avoid considering. According to Sen. Cornyn’s bill, the sale of CDs would generate $8.7 billion in economic output and support more than 20,000 U.S. jobs.