WASHINGTON (Reuters) - Japan’s ambassador to the United States weighed in on the U.S. presidential election debate on Friday by arguing against the “America first” stance of Republican candidate Donald Trump and stressing the importance of the U.S.-Japan alliance.

Republican U.S. presidential candidate Donald Trump speaks to supporters in Charleston, West Virginia, U.S. May 5, 2016. REUTERS/Chris Tilley

Without mentioning Trump by name, the envoy, Kenichiro Sasae, told a Washington forum Japan had come up unexpectedly in the election debate, showing that nothing could be taken for granted in terms of the long-standing alliance.

“In the presidential elections, there are arguments whether the United States is going for the isolationist stance,” Sasae said. “I don’t want to see that kind of United States.

“I want to see the United States to be strong and come with a strong robust position, not really thinking of the United States only,” he said.

Trump, the presumptive Republican nominee for the Nov. 8 presidential election, has portrayed Japan, a long-time treaty ally of the United States, as a free-rider on security. He has suggested Tokyo might need nuclear weapons to ease U.S. financial commitment to its defense, anathema to the only country ever attacked by atomic bombs.

Japan’s Minister for Regional Revitalization, Shigeru Ishiba, said comments by one candidate, who he said he would not name, were causing “a lot of concern in Japan.”

Ishiba told the forum that if Japan or South Korea chose to develop nuclear weapons regional stability would suffer, and added: “I don’t think it will add to the U.S. interest.”

“No matter who becomes the president, understanding the essence of the alliance, accurately grasping the international environment we have been placed in would lead, I am sure, to proper policies being implemented,” he added.

Sasae said he understood there was a debate about how to make America strong, but added “the question is whether you could be strong without a proper role around the world.”

“It is important not to undermine ... one, the value of the U.S.-Japan alliance; two, the geopolitical implications of emerging or resurgent powers in the world; three, the capability and strength of the United States.”

Trump outlined a clear “America First” policy in a speech late last month, vowing that if he were elected president, U.S. allies in Europe and Asia would have to fend for themselves if they did not pay more for the U.S. defense umbrella.

Japanese Prime Minister Shinzo Abe said on Thursday Japan’s U.S. alliance was the foundation of Asian peace and prosperity and Tokyo hoped to be able to work with whoever becomes U.S. president.