The Pentagon's decision announced Friday to take two heavy armor brigades out of Europe in 2013 and 2014 will not necessarily force NATO allies to shoulder more of the load if ground forces are needed for a large-scale conflict in the region, Gen. Raymond Odierno, the Army chief of staff, said Friday.

Odierno said the military will work hard to mitigate the impact of the shift on European allies, who rely heavily on U.S. military might to provide the bulk of the forces in a ground campaign.

The move to shift brigades out of Europe is part of a broader Pentagon plan to cut the size of the Army by 80,000 soldiers and restructure the service to ensure the military has the capabilities it needs to go to war. Odierno said the mandate to reduce the force from 570,000 soldiers during the height of the Iraq war to 490,000 by 2017 will force the military to rely more on the National Guard and reserves, particularly if the U.S. gets into two major, long-term combat operations at the same time.

Odierno said he is comfortable with the reduction in the force. But he suggested that the U.S. will now have to keep its reserve forces at a higher level of readiness than it did before the wars in Iraq and Afghanistan pressed tens of thousands citizen soldiers into service to buttress the active duty Army.

He also said his support for the force cuts hinges on the fact that the Army will have more than five years to make the reductions, largely through normal attrition. He acknowledged, however, that a small number of officers may have to be forced to leave.

As the Iraq war dragged on, the Pentagon had to recruit thousands of additional active duty soldiers and beef up and repeatedly tap reserve brigades in order to meet the combat demands there and in Afghanistan. For roughly eight years, the U.S. battled in both countries at the same time, stretching and straining the Army.

Meeting that type of commitment with an Army of 490,000 would not work, Odierno said.

"Do I have the capability to go into Korea and meet the requirements? Yes," he said, when asked about the risks of a smaller force. "Do I have the ability to stay there for 10 years? No."

If the military had to fight two large, simultaneous, long-term wars, he said, the U.S. would rely more heavily on its allies in the region and call for a massive mobilization of the reserves.

"Because of the fact that they (Guard and reserves) have been involved in combat operations for very long period of time, we are going to come up with a readiness model that will keep them at a little bit higher level than they have been in the past," Odierno told reporters during an interview in his Pentagon office. And if needed, he said, the U.S. would use reserves to "buy us time to increase the active component" to wage two large, intensive wars.

NATO allies have long relied on the U.S. ground forces to wage such conflicts, so cutting the European-based force in half will be met with reservations from those leaders.

But one senior defense official said the U.S. is working on a variety of options to compensate for the loss. Those could include further U.S. commitments to NATO's rapid response force, which includes up to 25,000 forces provided by the allies. There also will likely be additional multinational military exercises. The official spoke on condition of anonymity because the details have not been finalized.

Odierno said the two brigades being taken out of Europe — both heavy armor units — will be eliminated rather than reassigned somewhere in the United States. Both are based in Germany — the 172nd Infantry Brigade, currently in Grafenwoehr, and the 170th Infantry Brigade in Baumholder. That will leave two U.S. Army combat brigades permanently stationed in Europe, one in Germany and one in Italy.

Baumholder Mayor Peter Lang noted that the German military — which did away with conscription last year and is downsizing significantly — is closing two barracks in the area already.

"This is a second tough blow for our region," he told the dapd news agency. The Rhineland-Palatinate state interior minister, Roger Lewentz, said he was holding out hope, however, that the U.S. troops may not leave the area entirely, saying he planned a trip in May to Washington, where he would lobby for at least some logistical facilities to remain open

"In reality, I think in the long run this will benefit all of us," Odierno told reporters. He said U.S. Army units will be rotated in and out of Europe based on the training and other needs of the NATO partners. That system, he said, will allow more U.S. units to work with the allies and "we will be able to tailor our engagements based on their needs."

Over the long-term, U.S. officials said they are planning to slash the number of combat brigades from 45 to possibly as low as 32. The officials spoke on condition of anonymity to discuss planning. Odierno said eight brigades will be shelved over the next several years, and officials will decide in the next six months or so if additional units should go.

Officials said the changes will likely increase the size of each combat brigade — generally by adding another battalion — in a long-term effort to ensure that those remaining brigades are robust and able to perform their missions without straining the force.

A brigade is usually about 3,500 soldiers but can be as large as 5,000 for the heavily armored units. A battalion is usually between 600 and 800 soldiers.

"We will make our brigades more capable to operate across missions, will eliminate unnecessary overhead, and allow us to sustain more combat capability if we do this right," said Odierno, who did not provide any details about the restructuring.