Espousing his "America First" doctrine, Donald Trump has returned to power following his triumph in last year's U.S. presidential election.

His second inauguration ceremony was unusual in many ways. The venue was moved indoors into the Capitol Rotunda due to frigid temperatures, and the ceremony was significantly scaled back.

Among the few guests invited to attend the ceremony were members of the top echelons of major tech companies that made large donations, as well as overseas heads of state and foreign ministers. The ceremony was apparently intended to project the image of the world's celebration of his inauguration and emphasize Trump's authority.

Out in the towns, one could witness scenes reflecting the divisions in the United States. Some citizens took to the streets to protest against Trump's inauguration, while others including a far-right group that led the riot at Capitol Hill four years ago paraded with banners welcoming Trump back into office.

Fueling domestic divisions and widening the divide across the world -- does Trump believe this is the shape of the "great America" he aims to achieve?

Appalling claims for territorial expansion

Traditionally, U.S. presidents have called for cross-party unity in their inaugural speeches. Yet just as in his first term, Trump turned his back on this tradition, instead calling on people to come together for his version of America.

What stands out in his second term is the radicalism of his agenda.

Leading his priority list is getting rid of immigrants living in the country illegally. During his first term, Trump started by banning the entry of people from Arab countries. This time, he has adopted a harder line in his policies.

He stated that he would declare a state of emergency on the U.S. border with Mexico and send troops there. He also vowed to launch mass deportation of immigrants living in the U.S. without legal permission.

The target of exclusion extends to sexual minorities. Trump emphasized that there are only two genders, male and female, in an outright denial of gender diversity.

These policies could spark a new wave of nativism and promote discrimination.

Trump also startingly declared U.S. territorial expansion. He pledged to rename the Gulf of Mexico to the "Gulf of America," and to take back the Panama Canal, which he claims China is now operating. The canal was built by the United States and control was later returned to Panama.

He also expressed a desire to acquire Greenland, an autonomous territory of Denmark, under the pretext of ensuring U.S. national security in the Arctic, and refused to rule out the use of military pressure.

The inviolability of sovereignty is the basis of international law. The U.S. has condemned Russia for invading Ukraine in disregard of this principle.

Trump's other policies will also undermine international confidence in the United States. He vowed to introduce high tariffs on products from both rival countries and allies, but if this triggers tit-for-tat retaliatory tariffs, the global economy will lose steam.

His decision to pull his country out of the Paris climate accord and the World Health Organization could disrupt solidarity in the international community.

The possibility of countries following after Trump in self-righteous diplomacy is also concerning. If that happens, the world will be thrown into irreparable chaos.

Trump boasted that "the golden age of America" has just begun, and that the country will be "respected again all over the world." We hardly believe that's the case.

Japan should adopt proactive diplomacy

How should we deal with the new Trump era amid growing uncertainty?

First and foremost, we should discern how many of his policies will actually be implemented.

His anti-immigration policy will likely trigger a backlash at home, and the U.S. courts may rule it unconstitutional and order its suspension. In regard to his two-gender edict, a number of U.S. states opposing it may hammer out countermeasures to protect the rights of sexual minorities. It remains unclear whether he is really serious about territorial expansion or just eager to use it as a bargaining chip in diplomacy.

His ideology of "peace by force," or pressing for compromise with military might, is also fraught with dangers.

Trump claimed that he wants to be a "peacemaker." Amid Russia's prolonged aggression in Ukraine, his stance of pursuing a ceasefire should not be rejected. The problem, however, is that Trump may present conditions favorable to Russia, the aggressor nation, in a rush to mediate peace between the two nations. The international community must warn the U.S. against such a move to prevent the credibility of law and order from being undermined.

The fate of Washington's relationship with Beijing also remains uncertain. While Trump appointed anti-China hard-liners to his foreign and security policy teams, he may pursue compromise through bilateral talks with his Chinese counterpart when it comes to trade and other negotiations.

An escalation of U.S.-China tensions would not work favorably for Japan, which benefits from trade and investment with Beijing. Tokyo should proactively promote regional stability and contribute to easing such tensions.

For Japan, the greatest national interest is to maintain a free international order. The country has a significant role to play toward that end.