CANBERRA, Australia (AP) — Australia will send 11 military personnel to support a U.S.-led mission to protect cargo shipping in the Red Sea, but it won't send a warship or plane, the defense minister said Thursday.

Defense Minister Richard Marles said that Australia's military needs to keep focused on the Pacific region.

The United States announced this week that several nations are creating a force to protect commercial shipping from attacks by drones and ballistic missiles fired from Houthi-controlled areas of Yemen.

Marles said that 11 military personnel would be sent in January to Operation Prosperity Guardian’s headquarters in Bahrain, where five Australians are already posted.

“We won’t be sending a ship or a plane,” he told Sky News television. “That said, we will be almost tripling our contribution to the combined maritime force.”

“We need to be really clear around our strategic focus, and our strategic focus is our region: the northeast Indian Ocean, the South China Sea, the East China Sea, the Pacific,” Marles added.

The U.S. and its allies are concerned by China’s growing assertiveness in the region.

Australia is one of the United States’ closest military allies. Last week, the U.S. Congress passed legislation allowing the sale of Virginia-class nuclear-powered submarines to Australia under a security pact that includes Britain.

Marles rejected opposition lawmakers’ criticism that a failure to send a warship as the United States had requested made Australia a less reliable partner and ally.

“That’s patently ridiculous,” Marles said.

The U.S. is aware of the scale of the Australian defense force and the need to maintain its focus on the Asia-Pacific region, he said.

“It is to state the obvious that to take a major asset and put it in the Middle East is to take a major asset away from what we’re doing in the immediate region,” Marles said.

Opposition defense spokesman Andrew Hastie called on Australia to send a warship.

“It’s in our national interest to contribute. If we want others to help us in a time of need, we need to step up and reciprocate now,” Hastie said.

Several cargo ships in the Red Sea have been damaged by the attacks. Multiple shipping companies have ordered their ships not to enter the Bab el-Mandeb Strait until security is improved.