The Kremlin sharpened its accusations Wednesday in the wake of Turkey’s downing of a Russian warplane, as Moscow’s top diplomat called the incident a “planned provocation” that has dealt a major blow to already fragile relations with NATO. But Foreign Minister Sergei Lavrov also tamped down speculation of a military response by Russia after the jet broke apart in flames along the Turkish-Syrian border. “We’re not going to war against Turkey,” he said after talks with his Turkish counterpart. Still, Russia moved to strengthen its forces in Syria, saying new anti-missile systems would be deployed at an air base less than 20 miles from the Turkish frontier.