Tokyo, Japan - The US and Japan held joint exercises in a massive show of force against China even as the White House insisted that President Donald Trump has a good relationship his Chinese counterpart, Xi Jinping.

The Japanese joint chiefs of staff said that Wednesday's exercise with the US Air Force was conducted in "an increasingly severe security environment surrounding our country."

Tokyo alleged on Wednesday that two Russian Tu-95 nuclear-capable bombers flew from the Sea of Japan to rendezvous with two Chinese H-6 bombers in the East China Sea. They then proceeded to conduct a flight around Japan.

In response, Japan said that it had scrambled fighter jets and on Thursday stated that Tokyo had "confirmed the strong resolve of Japan and the United States not to allow any unilateral change of the status quo by force."

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In a separate statement it said that the "tactical exercises" involved two US B52 bombers, three Japanese F-35 fighter jets, and three Japanese F-15s.

Last week, Chinese military aircraft reportedly locked their radar onto a Japanese fighter jet, forcing it to take evasive maneuvers.

The incident sparked outrage from China, which denied that it had occurred, and spurred a strong response from the US, whose State Department said that "China's actions are not conducive to regional peace and stability."

"The US-Japan Alliance is stronger and more united than ever," a State Department spokesperson told the AFP. "Our commitment to our ally Japan is unwavering, and we are in close contact on this and other issues."

Despite striking an increasingly aggressive posture in the region, the White House insisting that Trump and Xi maintain a "good working relationship" despite the US' "very strong alliance" with Japan.

Tensions have escalated between Tokyo and Beijing since Japan's new rightwing Prime Minister Sanae Takaichi entered office in October.

Her threats to intervene militarily if China launched an invasion of Taiwan caused a diplomatic scandal, with Trump stepping in to calm things down by reportedly warning Takaichi to lay off the Taiwan issue.

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"Japan is a great ally of the United States as evidenced by their personal relationship and our continued trade relations with Japan," said White House Press Secretary Karoline Leavitt during a press briefing on Thursday.

"With respect to China, the president also has a good working relationship with President Xi, which he believes is a good thing for our country," she added.

"He believes that the United States should be in a position to have a good working relationship with China while maintaining our very strong alliance with Japan."