Two warplanes of Pakistani Navy fly above the sea during the AMAN-2011 joint naval exercise in Karachi, Pakistan, Mar 12, 2011. [Photo by Du Wenjuan/chinadaily.com.cn]

A Pakistan Navy's helicopter participates in an anti-piracy simulation during the AMAN-2011 joint naval exercise in Karachi, Pakistan, Mar 12, 2011. [Photo by Du Wenjuan/chinadaily.com.cn]

A Pakistan Navy's helicopter participates in an anti-piracy simulation during the AMAN-2011 joint naval exercise in Karachi, Pakistan, Mar 12, 2011. [Photo by Du Wenjuan/chinadaily.com.cn]