BRUSSELS (Reuters) - Russian President Vladimir Putin's actions in Crimea and eastern Ukraine may achieve what successive U.S. defense secretaries have failed to do -- persuade European NATO members to spend more on their armed forces.

The Ukraine crisis has been a reality check for NATO countries that believed they no longer faced a pressing military threat following the collapse of the Soviet Union.

After years of sharp defense cuts, partly forced on them by the financial crisis, there are signs that some NATO countries, particularly in central and eastern Europe, are ready to increase defense spending, or at least stop the slide.

Some, alarmed by Russia's actions in Ukraine, which is not a NATO member, are bringing forward purchases of weaponry.

The United States, NATO's dominant power, has seized on the Ukraine crisis to drive home its argument that European allies must spend more on their own defense. It is pressing for a formal commitment from the Sept. 4-5 NATO summit in Wales.

"I hope to see a common commitment to a gradual increase in defense investments," NATO Secretary-General Anders Fogh Rasmussen told Reuters in an interview this month.

"It won't be easy because many nations are still struggling with their economies and big deficits ... but what has happened in Ukraine is a wake-up call and a reminder that we can't take our security for granted," he said.

Over the last five years, Rasmussen said, Russia has increased its defense spending by 50 percent while NATO allies on average have decreased theirs by 20 percent.


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Ahead of the meeting between U.S. President Barack Obama and the other 27 alliance leaders, discussion have been held at alliance headquarters in Brussels over what the pledge will say.

"The actual text here is probably the hottest topic at NATO headquarters," a senior NATO official said.

Leaders are expected to pledge that, as their economies recover from the deepest economic downturn since the 1930s, they will increase defense spending, NATO diplomats say.

They are also expected to recommit to a longstanding NATO target that allies should spend the equivalent of 2 percent of their economic output on defense.

In 2013, only four of NATO's 28 members -- the United States, Britain, Greece and Estonia -- met the target. Even though it too is cutting defense budgets, Washington accounts for more than 70 percent of total allied military spending.

With NATO ending combat operations in Afghanistan this year, there is a scramble for savings, with hawks saying any savings should be spent on defense rather than be seized by finance ministers for other purposes.

In the same vein, U.S. officials have warned in increasingly stark terms about the dangers of Europeans slashing military spending. U.S. Defense Secretary Chuck Hagel said in May that Russia's actions in Ukraine had underscored the danger NATO allies have created by failing to meet their spending pledges.

In June 2011, one of Hagel's predecessors, Robert Gates, famously said NATO risked "collective military irrelevance" unless European allies boosted defense spending.

The 26 European NATO allies together spent nearly $270 billion on defense in 2013, still a large sum, but critics say some European nations spend too much on pay and pensions and not enough on modern equipment and deployable forces.

The 2011 Libya conflict, for example, revealed European deficiencies in air-to-air refueling and surveillance.