>> Russia's biggest war game since 2013 start on Thursday in Belarus. And many believe Moscow is testing its ability to wage war with the west. NATO says the exercises code named Zapad or West are much bigger than Russia has declared, involving some 100,000 troops and firing nuclear capable ballistic missiles.
Moscow says only 13,000 will take part. The last large-scale exercises in 2013 employed special forces training, longer range missiles and unmanned aerial vehicles. A year later, those tactics were used to annex Crimea. Reuters NATO correspondent, Robin Emmett.>> NATO's very nervous about these Zapad exercises. Mainly because of what happened in Crimea in 2014, and then Russia's direct support for separatists in Eastern Ukraine, and then the scope and swiftness of Russia's ability to move into Syria.
All these things caught NATO off guard, the NATO was wrong-footed and Russia, NATO says, just hasn't been clear about what it's actually doing in these exercises.>> NATO says it is calm and vigilant as it watches from the Baltics. But it thinks Zapad may be a simulated conflict with the US led alliance, showing Russia's power to mobilize mass troops at short notice.
>> NATO is trying to show that, if you like, it's the grown up in this, so it won't be doing a great deal of you watching, staying calm, and we'll have a few of its own small exercises. But, and NATO says these are annual exercises and they're unrelated.
There are some uncomfortable questions for NATO. Should NATO be doing something like this in the future? Clearly Russia's ability to mass huge numbers of troops at very short notice is a clear military advantage.>> The US Army chief in Europe has said Zapad could be a Trojan horse, used to make incursions into Poland and Russian speaking Baltic regions.
The Kremlin accuses NATO of building up forces on its frontiers as in the Cold War days. This US equipment arriving in Poland this week to shore up the alliance. But Russia says the West has nothing to fear from Zapad.