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U.S. Defense Secretary Chuck Hagel, left, meets with South Korean Defense Minister Kim Kwan-jin, right, Saturday, May 31, 2014 in Singapore. Hagel traveled to Singapore to attend the 13th Asia Security Summit. (AP Photo/Pablo Martinez Monsivais, Pool)

SINGAPORE (AP) — Defense Secretary Chuck Hagel says Russia's aggressive action in Ukraine was -- quote -- "a jarring gong of reality" that galvanized NATO allies.

Hagel tells an international security conference in Singapore that Russia's provocative actions, which include the annexation of Ukraine's Crimean Peninsula and the placement of thousands of troops along Ukraine's border, will force NATO nations to take another look at their defense budgets.

U.S. leaders have pressed NATO allies to increase defense spending and broaden efforts to cooperate and coordinate more on security. Hagel says NATO partners such as Poland have increased some defense capabilities.

Hagel is expected to attend a meeting of NATO defense ministers next week. Russia's actions have worried NATO nations and spurred more military training and fighter jet patrols in the region.