Reuters Russia and the US, the world's two most powerful militaries and biggest nuclear powers, appear set to clash over a chemical weapons attack in Syria. President Donald Trump is reportedly weighing a much bigger strike on Syria than the one on April 7, 2017, which did little long-term damage. Russia has threatened to shoot down incoming US missiles, and also target the platforms used to launch them, which could mean downing US Navy ships. The US and Russia, the world's two most powerful militaries and biggest nuclear powers, appear set to clash over a chemical weapons attack in Syria, and much of the world has gone quiet in anticipation. President Donald Trump has cancelled a trip to South America, and will instead consult with John Bolton, his new ultra-hawkish National Security Adviser.