MOSCOW — President Vladimir Putin of Russia ordered snap military drills as Chancellor Angela Merkel of Germany accused him of breaking international law in Ukraine and said NATO will defend member states against attack.

Combat readiness exercises are taking place “to defend the interests of the Russian Federation amid increasing threats to its security,” Defense Minister Sergei Shoigu said Thursday in a statement on the ministry’s website. Troops in Russia’s southern, central, and western military districts, naval deployments in the Black Sea and Caspian Sea, and airborne forces are involved, he said.

While Germany wants a “constructive relationship” with Russia, “we have to live with the reality” of its actions in annexing Crimea and backing separatists in eastern Ukraine, Merkel told reporters Thursday in the Estonian capital, Tallinn. Members of the North Atlantic Treaty Organization will stand together against any threats and are committed to protecting the Baltic nation that borders Russia, she said.