You are talking as if Putin's army is residing in Moscow and is not making any retaliation toward anybody. They should have expected that their army would have been hurt if they go to others' lands. Right?
Like China and the US, Russia are a big nuclear power with their own interests. Since they've recovered from the collapse of the Soviet Union in the last 5-10 years, they've been faced with an ultimatum from the west - get with our program or we'll make you. It should be any sovereign nations prerogative to pursue their interests in the way they please (excluding acts of war of course). Since Russia has been seen to be making it's inevitable recovery to becoming the power it once was and to add, not assimilate to the current world order, the US, the EU and NATO have done everything in their power to curtail Russia's pursuit of their own interests with it's partners.
Since the Arab Spring and the revolution in Ukraine, Russia has lost key allies which were economic partners and military footholds in regions where they already had comparatively little influence. Many of these revolutions are said to have been orchestrated or at least assisted by the US. It's not exactly a crazy conspiracy theory. First, the CIA are well versed in orchestrating coups; second, the majority of these revolutions happened to occur in nations not allied with the west; and third, the US have supported regimes in these nations that have pledged cooperation with the west.
Considering Russia's refusal to integrate into the status-quo had already been met with aggressive rhetoric and harsh sanctions, the concerted effort to influence regime change in the few countries Russia was allied with has naturally been seen as an act of aggression against it. Especially in Ukraine which is important to Russia economically and is a key buffer zone between it and the EU. Now Russia have western aligned states, a number of them NATO signatories, covering it's entire western border. Push back was inevitable. Russia invaded Crimea which is strategically key to them and they're supporting ethnic Russians fight for autonomy in eastern Ukraine. Now Russia is supporting the only established government institution in Syria as well. Hardly disproportionate reactions keeping in mind that NATO have deployed nukes in Turkey and Poland.
Putin is no angel but by contrast, Russia's military activity abroad hasn't even been a fraction as aggressive as the US. They're simply protecting pre-existing interests with old allies, not exponentially expanding them like the west. The US and NATO are still trying to twist Russia's arm and force them into submission but it's a very very dangerous game that they're playing.