Australia’s new defense minister on Wednesday talked down the prospect of Australia acquiring U.S. nuclear-powered submarines by the end of the decade, describing such a timetable as “optimistic in the extreme.”

Defense Minister Richard Marles, whose party came to power at elections last month, said his priority was closing a naval capability gap that is expected to open when Australia’s aging fleet of six Collins-class diesel-electric submarines begins to retire from 2038.

The United States and Britain have agreed to provide Australia with a fleet of submarines powered by U.S. nuclear technology. But when the agreement was announced in September, the first submarine was not expected to be delivered until 2040.

Former Defense Minister Peter Dutton said this month that the United States could be persuaded to provide Australia with two Virginia-class submarines from its Connecticut production line by 2030.

Marles, who is acting prime minister while Anthony Albanese is overseas, doubted Australia would have a single nuclear-powered submarine by 2030.

“I think that is optimistic in the extreme,” Marles told Australian Broadcasting Corp., saying the previous government had expected a delivery date in the 2040s. But he added, “We will be looking at every option available to try and bring that time forward."

Dutton, who is now opposition leader, said China would have the technology to detect Collins-class submarines in the South China Sea by 2035.

Unlike nuclear submarines, diesel-electric submarines have to surface and run on diesel-propulsion while they recharge their batteries. China is developing technology that would detect submarines on the surface, Dutton said.

Prime Minister Albanese plans to visit French President Emmanuel Macron in Paris this week to repair bilateral relations that soured in September when the previous Australian government tore up a 90 billion Australian dollar ($62 billion) contract for a French state-owned company to build a fleet of 12 diesel-electric submarines.

Albanese’s government announced recently that it had agreed to pay France’s Naval Group a 555-million-euro ($583-million) settlement for breaking the contract.

Lawmakers from the previous Australian administration said the new government had paid too much.

But Albanese pointed to bureaucrats’ estimates before a Senate hearing in April that breaking the contract was expected to cost AU$5.5 billion ($3.8 billion).

Albanese said his administration had brought that cost down to AU$3.4 billion ($2.3 billion) through the cooperation of Macron and the French government.

French anger over the canceled contract had delayed negotiations on an Australian free trade deal with the European Union.

Australia’s new Foreign Minister Penny Wong is visiting her birth country Malaysia to allay fears that the Australian move to nuclear propulsion could spark a regional arms race. She said Tuesday that her government was committed to ensuring the region remained peaceful, stable and prosperous.