Story highlights China's Ministry of National Defense says the report is "not true"

US official says Chinese military aircraft also being brought up to full readiness

Washington (CNN) China temporarily put cruise missile-capable bombers "on high alert" this week as the United States sees evidence the Chinese military was preparing to respond to a potential situation in North Korea, a US defense official told CNN.

The official said the United States has also seen an extraordinary number of Chinese military aircraft being brought up to full readiness as part of a military posture adjustment to increase its ability to respond.

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The alert status change was thought to be a temporary measure.

These recent steps have been assessed as part of China's effort to temporarily "reduce the time to react to a North Korea contingency," the official said. Such a contingency could include the risk of an armed conflict breaking out as tensions on the Korean Peninsula have increased in the wake of North Korean missile tests.

Chinese Ministry of Foreign Affairs spokesman Lu Kang said Friday he was "aware of the relevant reports" of a heightened alert in the Chinese air force but said he has "no information to give."

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