Has every country that could plausibly purchase the American fifth-generation F-35 Lightning II fighter done so? Not quite, but surprisingly, few countries are left in the world that could realistically purchase the fighter jet (especially after considering why the US has banned its export to various countries). For now, perhaps Portugal and Spain are the most likely countries to purchase the F-35 that haven't already.

The fighter jet everyone wants

Justin Bronks, a research fellow for Airpower and Military Technology in the Military Sciences team at RUSI, stated, "Despite its higher operating costs, every single air force that has been allowed to assess the F-35 directly against its European and US competitors has ultimately opted for the F-35—the operational capability in contested airspace is simply in a different class."

There are plenty more "wanna-be" buyers than actual buyers (especially in the Middle East). However, the United States doesn't sell its prized jet to anyone who asks.

As a rule of thumb, for a country to realistically purchase the F-35, it needs to meet a number of key requirements. Criteria include, being on very good terms with the United States (and generally considered a trusted ally), already operating multirole fighter jets, and not operating any Chinese/Russian equipment that the US considers could compromise the F-35 (like the Chinese 5G Huawei network or Russian Su-400s). Ideally, a country should be a member of NATO or be designated a major non-NATO US ally.

Refused by the United States

The use of the 5G Huawei network in the UAE is considered one of the reasons the US chose not to sell the jet to the UAE (after President Trump initially approved the purchase). Turkey's purchase of Russian S-400s is why the US kicked it out of the program. This would also disqualify Pakistan (which operates Chinese fighter jets and other gear), India (which operates Russian S-400s), and Malaysia (which flies Russian Su-30MKM fighter jets).

Most of the Gulf states are known to have wanted to purchase the F-35 but have been refused for various reasons (including to protect Israel's qualitative edge and because of Chinese 5G cellular networks in the region). It is always possible the US will sell the jet to some of these countries down the line.

The United States normally doesn't just refuse to sell F-35s to a partner or ally and leave them hanging. It normally offers a 4.5 or 4.5+ generation fighter compromise - like the F-16 Block 70 to Turkey or the F-21 to India (basically an F-16 on steroids).

It is also unlikely the US would sell the F-35 to Argentina (even though it is a major non-NATO US ally). That is because recent governments have shown a willingness to work too closely with China and that it would enrage the British over the Falkland Islands dispute (the British have an arms export ban on Argentina, and they produce 15% of the components in the F-35).

Taiwan is a special case. It is plausible the US will refrain from selling the jet to it because it would enrage the Chinese, risk espionage from many Chinese spies believed to be in the country, and it could fall into Chinese hands in the event of war.

Purchasing domestic

Two of the countries in Europe that would likely get the green light to purchase the F-35 if they asked are France and Sweden. However, these two countries wish to invest their resources into their own fighter jet programs (the Dassault Mirage/Rafale and Saab Gripen, respectively), and so have rested purchasing foreign fighter jets.

Likewise, Spain appears to have rejected the F-35 to purchase the Eurofighter Typhoon (which it partially makes). However, Spain will likely eventually purchase the F-35B to replace its aging AV-8B Harrier II jump jets in service in the Spanish Navy.

There are a few other potential European countries (Portugal is believed to be planning to purchase the F-35). Other countries could include Hungary, Bulgaria, Slovakia, and Croatia, but these countries seem to have chosen fourth-generation F-16s, Gripens, and Rafales instead.

Remaining possible F-35 buyers

For major non-NATO US allies, this leaves Colombia, Brazil, Morocco, Tunisia, Kenya, Kuwait, Jordan, the Philippines, and New Zealand.

Brazil is purchasing Swedish Gripens and possibly second-hand US F-16s. Given Brazil's close cooperation with China and Russia, the US may not supply the jets to Brazil (even though it is a major non-NATO ally). Kuwait and Jordan would likely be rejected for reasons similar to those of other Gulf states. Morocco would be an interesting case - the US has long enjoyed good relations with Morocco.

Kenya, the Philippines, and New Zealand lack multirole fighters (although the Philippines is starting to purchase them). It would be more likely for these countries to purchase fourth-generation fighters rather than go straight for the F-35.

Tunisia is possible, but the F-35 would be a major jump as the country only operates F-5 Northrop attack aircraft - F-16s might be a more predictable move. Other sub-Saharan African countries either have too close relations with Russia and China (like South Africa) or just don't see advanced fighter jets as a priority ( there are very few multi-role fighter jets in sub-Saharan Africa).

Mexico has a special relationship with the US. However, Mexico's military is a very low priority (outside policing actions), and it almost completely lacks a combat jet capability. Chile is the only country in Latin America currently flying F-16s (apart from Venezuela and before Argentina's second-hand Danish F-16s become operational). Chile is currently upgrading its F-16s.