A first group of six Ukrainian pilots is not expected to complete training on the U.S.-made F-16 before next summer, senior Ukrainian government and military officials said, following a series of delays by Western partners in implementing an instruction program for the sophisticated fighter jet. The timeline reflects the disconnect between Ukraine’s supporters, who envision F-16s as a key tool in the country’s long-term defense, and Kyiv, which has desperately requested that the jets reach the battle space as soon as possible, viewing them as critical for the current fight against occupying Russian forces. President Biden, after denying Ukrainian appeals...