WARSAW, Poland (AP) — Poland is planning a major realignment of its military structure because of the conflict in neighboring Ukraine, the country's defense minister said Monday, a move that could shift thousands of troops to its eastern border.

"The geopolitical situation has changed. We have the biggest crisis of security since the Cold War and we must draw conclusions from that," Polish Defense Minister Tomasz Siemoniak told The Associated Press.

Although Poland joined NATO in 1999, most of its 120,000-member army is based along the country's western border, as a relic of its former status as a Soviet bloc member.

That is going to change, Siemoniak said, adding that at least three military bases in the east will increase from the current 30 percent of capacity to almost 90 percent by the end of 2017. That's a potential increase of thousands of troops, although Siemoniak wouldn't specify a precise overall figure.

Up to 400 jobs would be filled in the air defense unit in Siedlce alone by 2017, he said.

"I believe that what happened to the east of Poland does not represent a threat to us for the next months, or two or three or five years. It is a need to draw conclusions for the decades to come," he added in explaining the large scope of the plans.

The announcement follows a visit by U.S. President Barack Obama to Estonia last month in which he urged NATO members to do more to assist Ukraine.

There was no immediate reaction in Moscow to the planned Polish military moves. The Russian government may be reluctant to criticize Poland since Russia had insisted on the right to position its forces as it wishes within its own country when confronted by the West over the deployment of Russian troops along the Ukrainian border.

Charles Heyman, editor of the Armed Forces of the United Kingdom publication, said Poland's eastward movement is "part and parcel" of a larger NATO re-deployment.

"We'll see other NATO nations probably stationing troops in Poland on a permanent basis as well," he said. "Not large numbers, but maybe a small NATO brigade of 2,500 that would be rotated every six months."

He said this would make it clear to Russia that "there are red lines that cannot be crossed."

"It gives the other side a message: You've gone far enough," he said.

In a restructuring after Poland became a democracy in 1989, the number of troops was gradually cut down from some 400,000 and the draft was discontinued, basing the armed forces on career officers and enlisted troops. Ever-limited means have been spent on upgrading the units, rather than on restructuring the whole infrastructure. Poland intends to increase its spending on the army to 2 percent of its GDP starting in 2016, from the current 1.95 percent.

Wedged between Germany and Russia, Poland has been the site of invasion and warfare. It was carved up by Nazi Germany and then-Soviet Union at the start of World War II, leading to the death of some 6 million of its citizens. Liberated by the Soviet Red Army, it was put under Moscow's domination for decades of communist rule after the war.

Poles value the independence they regained after the peaceful ouster of communism in 1989 and are worried by the Russia-Ukraine conflict.

"People have realized that security does matter and that you cannot forget about the army," Siemoniak said. "No one wants war."

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Associated Press reporters Lynn Berry in Moscow, Peter Leonard in Kiev and Greg Katz in London contributed to this report.