BRUSSELS • Six weeks before a critical summit meeting aimed at bolstering Nato's deterrence against a resurgent Russia, the alliance is facing a long list of challenges.
The first is to find a country to lead the last of four military units to be deployed in Poland and the three Baltic nations.
But that, analysts say, could be the least of its problems. Security concerns are as high now as they have been since the end of the Cold War. As the immigration crisis has strained relations within the continent, anxieties have been heightened by Russian military offensives in Crimea and eastern Ukraine, and a bombing campaign in Syria that has demonstrated Moscow's rapidly increasing capabilities.
Lately, Russia has talked openly about the utility of tactical nuclear weapons.
Despite the growing threats, many European countries still resist strong measures to strengthen Nato. Many remain reluctant to increase military spending, despite past pledges. Some, like Italy, are cutting back. France is reverting to its traditional scepticism towards the alliance, which it sees as an instrument of US policy and an infringement on its sovereignty.
And that is not to mention the declarations of presumptive Republican presidential nominee Donald Trump that Nato is "obsolete", that the allies are "ripping off" the United States and that he would not really be concerned if the alliance broke up. While that may be campaign bluster, it does reflect a growing unwillingness in the US to shoulder a disproportionate share of the Nato burden, militarily and financially.
The current concern, and a major element of what Nato secretary-general Jens Stoltenberg calls "the biggest reinforcement of collective defence since the end of the Cold War", is the decision to put four battalions of up to 1,000 soldiers each in those front-line countries bordering Russia.
While Britain, Germany and the United States have agreed to lead one battalion each, to be filled out with soldiers from other Nato allies to preserve the idea of multinational forces, leadership of the fourth is not yet in sight as the July 8-9 summit meeting in Warsaw approaches.
The US "is not thinking about doing two", said its ambassador to Nato, Mr Douglas Lute. "We're planning to do one and get our allies to step up" for the other three.
But other larger nations like Italy and France have declined. Italy cut military spending after pledging to increase it two years ago in Wales. Its leaders say it is already participating in a newly enlarged alliance rapid-reaction force.
The deployments are important, because these combat battalions are designed not to be simple tripwires, but to be large enough and sufficiently well equipped to do an invader real damage. Then they can be reinforced more quickly with the enhanced rapid-reaction force - another Nato and American decision is to station an added US armoured combat brigade of around 5,000 soldiers in Europe (for a total of three) and to preposition its heavy equipment such as tanks and artillery.
Poland is demanding that some of that equipment be prepositioned on its territory, but for the moment, most of it will go to Germany, Belgium and the Netherlands, which have storage and transport facilities dating from the Cold War.
Only now, in fact, is Nato actually surveying the infrastructure - the bridges, roads and railways - of relatively newer member states in Central and Eastern Europe, not having judged it necessary before to plan how to quickly reinforce them in case of a Russian invasion. Prepositioning in Eastern Europe would require large sums for capital investment to build special warehouses and infrastructure, Mr Lute said.
As Mr Stoltenberg points out, the effect of Russian policy has finally pushed European members of Nato to at least halt the decades-long decline in military spending. This year, he said, estimates are that European allies will as a whole increase military spending, something the US has been demanding.
NEW YORK TIMES