A US Navy helicopter and a fighter jet both crashed in the same half hour on Sunday during separate routine operations over the South China Sea, with all crew members safely rescued, the Navy’s Pacific Fleet said.

The Navy has launched an investigation into the cause of both incidents t hat occurred over strategic waters seen as a potential flashpoint for global conflict.

US President Donald Trump called the back-to-back crashes “very unusual” and raised the possibility of a fuel problem while speaking to reporters aboard Air Force One, en route from Malaysia to Japan on Monday.

“They think it might be bad fuel. We’re gonna find out. Nothing to hide, sir,” Trump said in response to a question.

The Navy said on social media that a MH-60R Seahawk helicopter went down around 2:45 p.m. local time “while conducting routine operations from the aircraft carrier USS Nimitz.” Search-and-rescue crews rescued three crew members, the Navy said.

About 30 minutes later, an F/A-18F Super Hornet fighter also crashed while conducting routine operations from Nimitz. Both crew members ejected and were safely recovered, the Navy said.

The F/A-18 is at least the fourth of the $60 million fighter jets the Navy has lost this year.

Bracketed by China and several Southeast Asian nations, parts of the vital South China Sea are claimed by multiple governments, but Beijing asserts ownership over almost all of the strategic waterway, in defiance of an international court ruling.

Over the past two decades, China has fortified its territorial claims by constructing military installations on contested islands and reefs. The US says China’s assertions and military buildup threaten freedom of navigation and free trade in the waterway.

US forces maintain a steady presence in the region to push back on Chinese sovereignty claims and support Washington’s allies and partners.

The aircraft crashes come amid Trump’s diplomacy tour in Asia, where he’s expected to meet with Chinese leader Xi Jinping this week for talks focused primarily on trade.

Relations between the two nations had soured in recent weeks after both slapped sweeping measures on the other following months of relative calm. Treasury Secretary Scott Bessent said Sunday that the US has reached a framework trade agreement with China, easing tensions before the highly anticipated meeting between Trump and Xi.

The Navy lost two other F/A-18s in the Red Sea during the spring, one falling overboard from an aircraft carrier and the other apparently having a problem with its landing system.

Another crashed off Virginia during a training flight in August.

The USS Nimitz, one of the largest warships in the world, is the oldest US aircraft carrier in service and is expected to be retired next year. (CNN)