We've now heard from the supreme commander of NATO in Europe, Gen. Philip Breedlove, that the 150,000 Russian combat troops on Ukraine's eastern border are "very, very sizable and very, very ready."

NATO on the other hand is "unwilling, unable and unready," at least if you go by some of its vocal military critics in recent years.

Breedlove would contest that description, and NATO remains, after all, the largest and most successful military alliance in history. The problem with history, however, is that the 28-nation alliance has seen better and certainly more coherent days.

From a military standpoint, the Ukraine crisis hits Europe at a time when its European members have slashed $45 billion from their militaries in recent years (the equivalent of the entire German defence budget).

Those cuts have left the U.S. to carry 75 per cent of the NATO burden, and they are coming at a time when Washington has been showing much less interest in European security, as it "pivots" its military strategy to the Pacific.

By contrast, Russian military spending has surged 92 per cent in just four years and will rise by 18 per cent this year, according to the authoritative Janes Defence Weekly military publications and Russian state figures.

Clearly, NATO did not expect to see this echo of the Cold War erupt, and defence analysts are wondering just how fit and flexible the alliance will be if tensions escalate further — not just along Ukraine's borders, but in other areas where NATO members abut Russia.

The immediate need is to ensure those same very ready Russian forces don't move into eastern and southern Ukraine, as they did in Crimea, to "protect" Russian speaking minorities, as Vladimir Putin would have it.

This would be a catastrophe for both Ukraine and the stability of Europe.

Stay out of Ukraine

At this point, it's clear that diplomats might have a few more tools than the generals to try and shore up Ukraine's independence.

These would include further economic sanctions against Putin's regime, more diplomatic isolation of Moscow, and urgent economic and technical assistance for Kyiv as it tries to build a democratic state free of the suffocating corruption that has crippled it almost since it became independent in 1991.

Another wrinkle here is that Europe has grown critically reliant on Russian energy supplies. And clearly a formula must be found to reduce Ukraine's and probably central Europe's dependence on Russian energy.

UKRAINE-CRISIS/DISMISSAL

Ukraine's new acting Defence Minister Mykhailo Koval, the former head of the Ukrainian border guard. His predecessor, Ihor Tenyukh, was let go over his handling of Crimea's annexation. (Reuters)

Militarily, however, the kind of help that has been discussed for Ukraine's poor-cousin armed forces is strikingly limited.

It would include some technical support, satellite intelligence and communications upgrades to counter any cyberwar. Plus real uniforms and "military meals."

Ukraine, of course, is not a member of NATO, and too much involvement by the alliance at this point would almost certainly heighten tensions dramatically.

Offering to shore up Ukraine's military, NATO believes, would be a step much too far in a country for which Russia has deep emotional ties and considers part of its, though now much reduced, sphere of influence.

Concern about provoking Russia unnecessarily was why so many in NATO were always cool to Ukrainian membership whenever it was brought up.

One of the strongest opponents of Ukrainian membership in NATO was the former Cold War-era diplomat /strategist Henry Kissinger, who continues to warn that such a move would topple Europe's delicate balance of powers.

"Far too often the Ukrainian issue is posed as a showdown: whether Ukraine joins the East or the West," he wrote last week in the Washington Post.

"But if the Ukraine is to survive and thrive, it must not be either side's outpost against the other — it should function as a bridge between the two."

One for all?

Even leaving Ukraine aside, NATO has other potential crises on its flanks, where it is obliged by treaty to protect increasingly nervous NATO members who are also neighbours of Russia.

These include the three former Soviet Union satellites, Estonia, Latvia and Lithuania, all with fragile economies and significant Russian minorities; as well as the much larger Poland, a former member of the Soviet Union's Warsaw Pact military alliance.

Including Estonia, Latvia and Lithuania was always controversial within NATO because they are so far east and so difficult to defend.

Still, they made it in and now demand NATO show it would be ready to honour its famous (Article 5) guarantee that an attack on one member involves an attack on all.

In recent weeks, the U.S., with U.K. support to come, has rushed in limited fighter plane and other  air support for the Baltic members, as well as 300 support staff and some naval units.

UKRAINE-CRISIS/

Russian sailors mill about onboard the Suzdalets at the Crimean port of Sevastopol earlier this week. As many as 150,000 Russian troops are also taking part in exercises along Ukraine's eastern boundary. (Reuters)

But so cautious a response has not eased the nervousness in the region, which has been warning NATO for years about Russian ambitions.  

Some of their fears stem from the large military exercises Moscow has run in the Baltic region in recent years, including some that simulate attacks on Lithuania and Poland.

NATO, it should be noted, also exercises units in the Baltic region, while Poland has recently launched a substantial arms buildup of its own in response to Russia's.

These days, NATO is also hearing rising security concerns and demands for reassurance from nations such as Hungary, Romania and Bulgaria , as well as both the Czech and Slovak Republics.

Here, NATO's worries are not limited to military pressure-tactics, but encompass the deep political crises and anti-democratic trends in some of these Eastern Europe countries, where crony-capitalism and the leverage of Russian gas supplies open new doors to Putin's influence.

No, this is not the old Cold War. Today's Russia is weaker than the West, even with few European powers ready for yet another arms race with Moscow.

But if Putin's regime really does feel that NATO's once triumphant march to the east is at least in part reversible, given the right pressure points, then NATO's very credibility is about to be severely tested, yet again.