Ukraine faces defeat as early as next summer if American and Nato military aid dries up, a senior US official has warned.Vladimir Putin’s chances of victory have been buoyed by war fatigue and blocks on funding in both America and the EU.“There is no guarantee of success with us, but they are certain to fail without us,” a senior US military source told CNN.Viktor Orbán, Hungary’s prime minister, last week blocked a £43 billion EU aid package for Ukraine.Austria had also threatened to block the bill until Kyiv toned down criticism of an Austrian bank still working in Russia. Western...