Prime Minister Shinzo Abe and visiting U.S. President Donald Trump reaffirmed in their Nov. 6 talks in Tokyo that the two countries are united in trying to ramp up pressure on North Korea, which continues pursuing nuclear and missile programs.

The two leaders displayed their strong ties afresh during Trump’s visit to Japan, the first leg of his five-nation Asia tour.

In a joint news conference after their meeting, Abe stressed his united front with Trump, saying, “I completely agreed (with Trump) that Japan and the United States will intensify pressure to the highest level.”

But pressure is only a means to open the door to dialogue. Tokyo and Washington should make tenacious diplomatic efforts to achieve that goal.

A key diplomatic challenge is how to win support for the agenda Japan and the United States shared to deal with the North Korean situation from not only South Korea, China and Russia but also other Asian countries.

In particular, it is vital to get China, North Korea’s close ally, on board.

Unsurprisingly, Abe and Trump agreed on the importance for China to play an even bigger role in international efforts to resolve the situation.

What should be noted here is the initiative to promote a “free and open Indo-Pacific region” the two leaders touted as a common Asian strategy for Japan and the United States.

The initiative envisions cooperation led by Japan and the United States plus India and Australia to build an open order in a region spanning from the Pacific to the Indian Ocean underpinned by such principles as the freedom of navigation, the rule of law and fair and free reciprocal trade.

It is meaningful that the Trump administration, which has an inclination to focus on America’s own interests, is engaged in playing an active role in Asia.

But it is necessary to avoid making the Indo-Pacific strategy appear intended as a rival to Chinese President Xi Jinping’s “One Belt, One Road” initiative to create a vast economic zone stretching from China through Central Asia to Europe.

Any rivalry between the Japan-U.S. alliance and China over regional leadership could make members of the Association of Southeast Asian Nations (ASEAN) uneasy. The ASEAN countries are averse to any friction with China.

If Japan and the United States want China to play ball with them in dealing with North Korea, it would be wise to avoid making the Indo-Pacific strategy look like an attempt to keep China’s growing presence in check.

While Trump is scheduled to visit China from Nov. 8, Abe is seeking to meet Xi and Russian President Vladimir Putin on the sidelines of the summit of the Asia-Pacific Economic Cooperation forum, which starts on Nov. 10, and other occasions.

Abe needs to demonstrate his diplomatic prowess by winning cooperative responses from the Chinese and Russian leaders to the efforts to deal with North Korea that he and Trump agreed on.

One surprise that emerged from the Nov. 6 joint news conference was Trump’s blatant call to Japan to purchase more U.S. weapons as a way to reduce the U.S. trade deficit with Japan.

Trump said it is very important that Abe “is going to be purchasing massive amounts of military equipment, as he should. …. It’s a lot of jobs for us and a lot of safety for Japan.”

It is not appropriate to link a pressing security concern with a trade issue. It should be up to Japan to decide on weapons purchases based on its own needs.

If Trump is serious in promoting the influence of Japan-U.S. solidarity widely in Asia, he needs to refrain from making remarks that could cast doubt on America’s motives.