The G-20 meetings in Hamburg present a dangerous challenge to Donald Trump as he tries to both burnish his own reputation and improve the overall global financial and social situation. To meet the rest of the world head on, he has to control the demons inside himself, by avoiding the extemporaneous gaffes that all too often have upended his substantive agenda.

He must not be distracted, moreover, by peripheral domestic political quarrels. He did well in Poland to state that the Russians had no monopoly in seeking to meddle in internal U.S. affairs. He now needs to take the initiative by talking tough to Putin and Russia and Xi and China. Unfortunately, the time is long past to think that they will work cooperatively to reduce aggression and instability in North Korea or Syria. Knowing that he has to be sure to take unambiguous steps to strengthen the NATO in order to meet a rising totalitarian threat.

He must also be prepared to take on Angela Merkel and Germany on the two great blots of her faltering administration. Her intransigence on Brexit is ill-advised. A trade deal on the movement of capital, goods and services between the EU and the UK has to be her first order of business. He must also take the offensive on energy policy and global warming. He should defend the expanded use of fossil fuels, in contrast to the foolish German reliance on a losing combination of dirty coal and unreliable wind and solar energy.

Finally, he must urge all the participants of the G-20 to reject head-on the so-called social justice demands of the legions of protestors outside the gates, whose own policies will lead to universal decline in living standards for the poor around the globe.

On the negative side of the ledger, Trump has to be aware that his own views on trade and immigration do not stand up to close analysis. The constant fetish over trade deficits should take a back seat to policies that encourage the free movement of goods and services across national lines. The principle of comparative advantage still applies: the nation that does not import needed goods and services abroad will be ill-equipped to produce high-quality goods at low prices for sales in the international market.

Trump also has to show a much better awareness of the human rights dimension associated with immigrants and refugees, many of whom cannot go home, if he hopes to make American policy a lodestar for world action. Sure, the U.S., Germany, and Sweden cannot succeed with open borders. But given the dangerous world situation, he should stress the willingness to supply financial aid to reduce the plight of displaced persons, and move with more military force to remove the rogue governments whose policies have led to the death of hundreds of thousands of people and the displacement of millions more.

A tough agenda, but doable if he sticks to a serious game plan.