After a brief greeting with Polish and American troops and a tour of F-16 fighter jets, Obama and his Polish host spoke briefly about their security cooperation and the pall that events in Ukraine have cast on the region.
"As friends and allies we stand united together and forever," Komorowski said.
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Obama said he was starting his visit in Warsaw because America's commitment to the security of Poland and its allies "is sacrosanct," alluding to additional measures to increase the U.S. commitment to Poland's security.
The White House said Obama will call on Congress to support a "European Reassurance Initiative" of up to $1 billion to increase U.S. military rotations on the continent, plus boost exercises, training and the responsiveness of U.S. forces to reinforce NATO.
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"These efforts will not come at the expense of other defense priorities, such as our commitment to the Asia Pacific rebalance," the statement said.
The effort would involve increased participation by the U.S. Navy in NATO naval force deployments, including "more persistent deployments" to the Black and Baltic seas, the White House added.
—By NBC News. Reuters contributed to this report.