ISTANBUL — US President Donald Trump on Saturday blamed his predecessor, Barack Obama, for Turkey’s decision to buy advanced Russian missiles that his administration has warned could endanger NATO security and pledged to find a way out of the dispute that has rattled the countries’ decades-old alliance. 

Yet Trump stopped short of announcing a breakthrough with his Turkish counterpart, Recep Tayyip Erdogan, with just weeks to go before Turkey takes delivery of the Russian-made S-400 Triumph. That acquisition will put Turkey at risk of US economic sanctions and expulsion from the Pentagon’s F-35 fighter jet program. Turkey says it needs the Russian weapons, widely considered the most advanced antiaircraft system available, because Washington has refused to transfer technology with its own offer of American missiles.

“We have a complicated situation because the president was not allowed to buy the Patriot missiles, so he bought the other ones — the S-200s [sic] or 400s,” Trump said. “He wasn’t allowed by the Obama administration to buy it until after he made a deal to buy other missiles. So he buys the other missiles, and then all of sudden, they say, ‘Well, you can now buy our missiles.’ You can’t do business that way. It’s not good.”

However, the Obama administration agreed in 2013 to sell Turkey American Patriot missiles. Under Trump, the State Department also cleared the sale, estimated at $3.5 billion, in December.