Incoming presidents often proclaim that they intend to concentrate on domestic affairs and not get distracted by foreign policy. All agree that President Biden must focus on the pandemic and attendant economic troubles. But foreign-policy dilemmas will quickly intrude. Choices won’t be easy.

Israel and Iran are lurching from episodic jabs to full-scale war. Tehran vows revenge against Israel and possibly the U.S. for the assassination of a top Iranian nuclear scientist. Tensions, building for years, include Israeli air strikes on Iranian bases in Syria. (Why does Putin permit Israeli air strikes? An undisclosed side-deal is going on here.) Iran’s client Hezbollah has 100,000 to 150,000 rockets in Lebanon. How long would Israel tolerate a thousand-or-so Iranian missiles a day hitting them? Not long.

After Trump pulled out of the 2015 Iran nuclear deal that inspects and limits Iranian fissile material, Tehran increased refinement, arguing that without nuclear weapons they will always have to back down in the face of America’s and Israel’s nukes. Biden’s vow to rejoin the six-party agreement will produce an angry collision with Israel. If he continues Trump’s policy of “maximum pressure,” expect Iranian nukes and soon Israeli air strikes. Either way, trouble.

Iran could build a nuclear device within a year or two. How close to completion would Israel wait? After a quarter-century of quiet contacts, conservative Arab monarchies on the Gulf have opened diplomatic relations with Jerusalem and would be delighted to refuel Israeli jets on their way to bomb Iran. The Arab dictum “The enemy of my enemy is my friend” is in full operation.

Can the U.S. stand aloof from a war across the Persian Gulf? Trump seems to invite collision with Iran. Would one or more American carrier battle groups in the Gulf deter or provoke Iran? Iranian speedboats practice “swarming” against American warships. We could soon be driven to invade and occupy Iran. Or bow out of the Gulf. Biden may have to make such a choice. Anyone for another Mideast war?

Pulling all U.S. forces out of the Persian Gulf is tempting, but neither Obama nor Trump has done so. Why? Our military and intelligence agencies forcefully argue that abandonment will lead to even bigger chaos and war. Must we forever stabilize the Gulf? If we don’t, can we live with chronic instability? Do we let Moscow establish bases and influence in the Middle East, something Russia has sought since the tsars? We used to strenuously oppose that.

India and Pakistan have fought four wars, and both have nuclear weapons. Kashmir is the permanent iritant, but Indian Prime Minister Modi’s Hindutva (Hindu-ness) aims at crushing India’s Muslim minority. Pakistan’s Inter-Services Intelligence trains and arms Muslim terrorists, who provoke Indian retaliation. Must we take sides? We “tilted” to Pakistan in their 1971 war over Bangladesh, something U.S.-India relations took years to recover from.

China, reviving its ancient superiority complex, sees a paralyzed, declining U.S. American critics claim Trump is producing precisely that. Washington’s dilemma: how to deter China’s modernized military without escalating into war. How many ships should we deploy in the China Seas? Do we risk puting U.S. carriers within range of Chinese missiles? Would a “Quadrilateral” of the U.S., Australia, Japan and India dissuade China? Not yet an alliance, it needs an economic basis in the Trans-Pacific Partnership, which Trump dropped out of. Will Biden rejoin the TPP?

Trump’s tariffs on Chinese and European imports fixed nothing; the U.S. trade balance worsened. The tariffs hurt American fabricators, importers and consumers, not Beijing. China — with its RCEP trade pact, Belt and Road Initiative and wider use of Chinese currency — glides into the role vacated by the U.S. The dollar, still the world’s standard trading currency, may need realignment, which could be as disruptive as Nixon’s closing of the gold window in 1971. Biden will have to restore the World Trade Organization to stabilize trade flows and settle disputes.

A new report finds microwave attacks injured American diplomats in Cuba, China and Russia. Scientists think the hardware was (is) Russian. Russian intel probably also operated it. Even worse, it was recently discovered that Russian intel hacked just about everything, undetected, for months. Is our cybersecurity asleep? Biden is under pressure to retaliate, worsening already strained U.S.-Russia relations. Good. Post-Trump, we can get decisive with Moscow.

Central America continues to break down. Drought, hunger and murderous gangs drive Mesoamericans to the U.S. Do we dissuade them by stronger barriers? Caging their children? Better idea: major U.S. aid programs that reform corruption, fight crime and jumpstart economic growth. It would not be easy or cheap but much better than endless, failed efforts in the Persian Gulf. Redirecting U.S. resources to our own hemisphere could be Biden’s signature and lasting foreign-policy achievement. Think: close to home.