Moscow - Russia's President Vladimir Putin on Thursday called for reinforcing the country's military nuclear potential and making sure its missiles can penetrate any missile-defence systems."We need to strengthen the military potential of strategic nuclear forces, especially with missile complexes that can reliably penetrate any existing and prospective missile defence systems," Putin said at a defence ministry meeting, quoted by Russian agencies."We must carefully monitor any changes in the balance of power and in the political-military situation in the world, especially along Russian borders and quickly adapt plans for neutralising threats to our country."He said Russia's military had successfully shown its capabilities in Syria. "The Syrian army received considerable support, thanks to which it carried out several successful operations against militants."Russia has flown an air campaign in Syria since September 2015 in support of President Bashar al-Assad, with its special operations contingents also operating on the ground in the country.Defence Minister Sergei Shoigu said the military has "tested 162 types of modern armaments during military campaign in Syria," including its Sukhoi warplanes and MiG and Kamov helicopters."They have shown to be highly effective," he said.