Ten-day military exercising, Anaconda-2 016, will involve 31,000 troops and thousands of vehicles from 24 countries

The largest war game in eastern Europe since the end of the cold war has started in Poland, as Nato and partner countries seek to mount a showing of strength as a response to concerns about Russias assertiveness and actions.

The 10-day military exercising, involving 31,000 troops and thousands of vehicles from 24 countries, has been welcomed among Natos allies in the region, though defence experts warn that any mishap could inspire an offensive reaction from Moscow.

A defence attache at a European embassy in Warsaw said the nightmare scenario of the exercising, named Anaconda-2 016, would be a mishap, a miscalculation which the Russians construe, or choose to construe, as an offensive action.

Russian jets routinely breach Nordic countries airspace and in April they spectacularly buzzed the USS Donald Cook in the Baltic Sea.

The exercise, which US and Polish officials formally launched near Warsaw, is billed as a test of cooperation between allied commands and troops in responding to military, chemical and cyber threats.

It represents the biggest movement of foreign allied troops in Poland in peace time. For the first time since the Nazi invasion of Soviet-occupied Poland began on 22 June 1941, German tanks will cross the country from west to east.

Managed by Polands Lt Gen Marek Tomaszycki, the exercising includes 14,000 US troops, 12,000 Polish troops, 800 from Britain and others from non-Nato countries.

Multinational operations publicised in so far include an airdrop involving 1,130 parachutists over the northern Polish city of Toru on Tuesday including 500 US troops and 230 British ones engineers building a bridge to carry 300 vehicles over the Vistula river and a night-time assault involving 35 helicopters.

Marcin Zaborowski, a Polish defence analyst at the Centre for European Policy Analysis in Warsaw, told: In Poland we assure the exercising as a reassurance measure from the US and Nato. The defence needs of central and eastern Europe are real. The scope and number of Anaconda are no match for the Russian exercises that go on all the time just across the border.

War game map

But Zaborowski also acknowledged that the backdrop to the exercising was tense, and accidents can happen.

Anaconda-2 016 is a prelude to Natos summit in Warsaw on 8-9 July, which is expected to agree to position significant numbers of troops and equipment in Poland and the Baltic nations.

It comes within weeks of the US switching on a powerful ballistic missile shield at Deveselu in Romania, as part of a defence umbrella that Washington says will stretch from Greenland to the Azores.

Last month, build run began on a similar missile interception base at Redzikowo, a village in northern Poland.

The exercise goes at a sensitive time for Polands military, following the sacking or forced retirement of a one-quarter of the countrys generals since the nationalist Law and Justice government came to power in October last year.

So harsh have the cuts to the top brass been that the Polish armed forces lately determined themselves unable to provide a general for Natos multinational command centre at Szczecin.

Insiders tell morale has fallen to an all-time low since the appointment of Antoni Macierewicz as defence pastor.

Professional soldiers are particularly worried about a lack of lucidity surrounding the creation and role of a 17 -brigade territory army, describe in part from the 35,000 members of Polands gun clubs and paramilitary groups, some of which, it is feared, are linked to the countrys racist football rowdies. Two of the volunteer brigades are set to assist the professional Polish army during Anaconda.

The Guardian understands from military sources that there has been little consultation over legislators long-term vision for the volunteers, described last week by the plenipotentiary pastor Grzegorz Kwaniak as a fifth force after land, sea, air and special forces.

A western defence expert confirmed that there was concern about government interference in Polands military. Poland is highly regarded internationally. In the past 15 years, they expended a lot of money and generated one of the best armies in the region. They attained big sacrifices in Afghanistan. They lost 40 soldiers. It is not clear what the government thinks it needs to improve, he said.

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