President Barack Obama’s visits this week to Vietnam and Japan are his latest high-profile demonstrations of America’s enhanced focus on the Asia Pacific.

As a scholar of East Asia and its politics, I have studied the relationship between the US and the region for more than 40 years. I believe the president will emphasise the upbeat prospects for relations between the US and Asia. The president will also be sending a not-too-subtle message to potential military challengers.

America seeks a peaceful and economically prosperous East Asia, but our ties to countries like Japan and Vietnam must also remain robust to rebuff any untoward military challenges from elsewhere in the region.

Talk of peace and prosperity

I predict the president will stress the region’s promise as a showcase for economic integration and peaceful development, and praise the historical transformation of America’s relations with both Japan and Vietnam. US-Japan ties have been positive since the end of World War II. Ties with Vietnam have seen astounding progress since they were normalized in 1995.

In a briefing last week, Ben Rhodes, the deputy national security advisor, said the president’s message in both countries will be “forward-looking”.

Rhodes said it would:

reflect on and confront directly and engage in dialogue about our history… [because] we are focused on the future we’re trying to seek – a future of greater peace and cooperation, of nonproliferation going forward.

Obama will likely cover myriad topics during this visit, including the mutual benefits expected from the 12-nation Trans-Pacific Partnership to which all three countries are parties.

In Vietnam, the president will also meet with a variety of civil society groups as part of America’s commitment to human rights and inclusive governance. In Japan, he will visit Hiroshima – the site of the first atomic bombing – where he will likely urge the world to be mindful of the devastating human toll of wars and nuclear proliferation.

Military links are expanding

Nevertheless, the military and security implications of Obama’s visit will not be far from the surface.

Japan and the United States have, over the last decade, substantially deepened their strategic connections. Japan’s 2014 National Defense Program Guidelines take major steps to advance the sophistication of Japanese military planning and operations. The guidelines also match, more closely than ever before, US security planning.

The Japanese parliament also recently adopted policies permitting its military to engage in previously banned “collective defense.” This measure expands the geographical and strategic range of US-Japan military cooperation and allows Japan’s Self Defense Forces to act in defense of that country’s allies, most importantly the United States.

In Vietnam, President Obama has been particularly keen to boost bilateral ties. This began with his administration’s announcement of the comprehensive partnership in July 2013. He was also vigorous in his commitment to make Vietnam a participant in the TPP, despite the fact that its economy is further from meeting its standards than are those of most other participating countries.

Joint defense relations with Vietnam have also witnessed a number of notable developments. They include the easing of the lethal arms embargo in October 2014 and the signing of a new framework for defense ties in 2015. And after landing in Vietnam, Obama went further and ended the longstanding embargo on US weapons sales to Vietnam.

Balancing regional challenges

China and North Korea are not far from Obama’s calculations.

North Korea, under its young President Kim Jong-un, has rejected efforts at cooperation from the US and South Korea. Kim has opted instead for a series of nuclear and missile tests in defiance of United Nations sanctions while spewing hot-throated threats of annihilation in the direction of Japan, South Korea and the United States.

North Korea has been a steadily rising threat. But the North is almost certain to be completely destroyed in any full-scale war, according to a majority of security experts with whom I’ve spoken. I believe its regional threats remain limited to annoying provocations and its real challenge comes from nuclear proliferation.

China poses a different type of threat: namely, slow-but-steady maritime expansions that worry the US and other Asian countries. China continues to emphasise its contentious Nine Dash Line, with implicit claims that the South China Sea is little more than a Chinese lake. It has also been rapidly turning contested rocks and atolls into militarily occupied islets, in what Admiral Harry B Harris Jr, the commander of the US Pacific fleet, has called a “great wall of sand.”

Chinese actions seem to reflect their leader’s conviction that China is rising while the US is declining. Or, as Foreign Minister Yang announced in apparent frustration when 12 nations at the 2010 Association of Southeast Nations meeting challenged Chinese assertiveness in the South China Sea, “China is a big country and other countries are small countries and that’s just a fact.”

Such looming challenges lie behind Obama’s visit which represents another step in his administration’s ongoing efforts to shape the choices made by potential adversaries.

As Obama has said, the US will extend a handshake when aggressors unclench their fists. At the same time, the US will resist reshaping the status quo by using military force. The American president’s visits to Vietnam and Japan will telegraph this message with unmistakable clarity.

TJ Pempel, Professor of Political Science, University of California, Berkeley

This article first appeared on The Conversation.