.... But the danger with the crisis in Ukraine is the law of unintended consequences.
If Russia or its proxies were to misjudge the situation and overstep by destabilizing Ukraine on its borders with Poland, Hungary, Romania or Slovakia - all EU and NATO member states - events could easily spiral out of hand.
The same situation pertains to Estonia, Latvia and Lithuania, the only NATO and EU states that were once part of the Soviet Union itself, and which increasingly feel threatened by Moscow.
Under Article 5 of NATO's treaty, an attack on one member state is deemed an attack on all.
Alliance officials say their mandate limits NATO's reach - it cannot act in Ukraine because Ukraine is not in NATO. Nevertheless, the mandate has proven flexible in the past when Washington and its allies had the political will to act: NATO's three wars of the past generation, in Afghanistan, Kosovo and Bosnia, were all fought outside the territory of its members.
But even if NATO is not prepared to fight for Ukraine, the mutual protection pact means that it could be drawn into a conflict, if a NATO member that borders Ukraine or R were to be attacked or threatened.
While such a scenario appears unlikely, the annexation of Crimea seemed almost equally so three months ago.
What is more, R has doubled its military spending since 2004 while most NATO member states have sharply curtailed theirs as a result of the economic crisis.
NATO's superpower Washington still spends around eight times as much on weapons as Moscow, but many of its European allies would struggle to field a force that would frighten R.
Given the desire to avoid confrontation, NATO will do everything it can to stick to verbal pressure to contain R. Yet that runs the risk of convincing Moscow that NATO is ultimately toothless, a relic of an earlier era.
That in turn could lead to another dangerous scenario. If R or its proxies go too far and Ukraine's army retaliates, a full-on military conflict could erupt in Ukraine, a country of 45 million people as large as France.
At that point, given the threat to Europe's security and the grave risk to so many lives, the EU and NATO may decide there is an overriding humanitarian obligation to intervene, even if military involvement is the last thing they want.
That would in many ways mirror NATO involvement in Bosnia in the early 1990s, which began with monitoring in coordination with the United Nations and steadily grew into combat air operations and the deployment of 60,000 soldiers.
R may be counting on NATO to keep clear. But if history is any guide, a steady escalation in Ukraine runs the risk of sparking events that the West, and by extension NATO, could find it cannot ignore, despite its best intentions. ...
fought with nukes. 
