Pilots first heard about a Chinese live-fire naval exercise near Australia last week when already in the air, receiving messages that forced some to change paths through a busy air corridor, satellite text messages to and from pilots seen by Reuters show.

Australia learned about Chinese live-fire naval drills off the country’s coast that forced dozens of flights to be diverted via an alert from a commercial pilot, authorities said on Monday.

China carried out a “joint combat readiness patrol” drill on Wednesday in an area 40 nautical miles off Taiwan that included live fire drills, according to Taiwan’s Ministry of National Defense, which condemned the drills and dispatched military forces to monitor the drills.

A series of unexpected live-fire drills by Chinese naval vessels in the Tasman Sea has sparked criticism from Australia and New Zealand and raised questions over regional security. The exercises were conducted by a trio of warships in the international waters beneath a busy commercial flight path,

New Zealand raised fresh concerns Monday over nearby live-fire drills conducted by Chinese warships armed with “extremely capable” weapons, an unprecedented show of firepower last week that analysts say are part of Beijing’s ongoing plan to build a blue-water navy with global reach.