Like a timebomb waiting to go off, Europe’s smouldering immigration problem exploded into a full-blown crisis last week. The US experienced a similar delayed upheaval, after the human consequences of Donald Trump’s “zero tolerance” border policy became too painful to ignore. The two events are closely linked, the product of systemic international failings.

The longstanding inability of governments to cope with challenges posed by the increased flows of refugees, asylum seekers and economic migrants is common to both sides of the Atlantic. The ensuing vacuum has been filled by opportunists such as Trump, maverick fringe parties, andrightwing zealots such as Italy’s new interior minister, Matteo Salvini, and the US attorney general, Jeff Sessions.

Chaos in Congress, where Republicans and Democrats have argued over conflicting plans to end incarceration of immigrant children on the Mexican border, enabled Trump to claim he was addressing Americans’ concerns. The US president has backed off for now, but his tough approach remains popular. Likewise, Salvini’s approval rating has soared after he banned a ship carrying migrants from Libya.

In Germany, Angela Merkel’s domestic public standing has never wholly recovered from her decision to admit 1.1 million refugees in 2015. Although the total annual influx into Europe has plunged to under 40,000 people so far this year, polls suggest about two-thirds of German voters agree with Horst Seehofer, the interior minister and the chancellor’s rebellious ministerial rival, that tougher border controls are necessary.

Merkel is scrambling to agree a Europe-wide policy at next week’s EU summit. She and other national leaders will first hold an emergency meeting in Brussels on Sunday. But Poland, Hungary and other central and east European opponents of her “burden-sharing” approach will not alter their stance. Attitudes among the “frontline states” – Greece, Italy and Spain – are hardening. As in Washington, there is no European consensus.

The latest proposed sticking plaster – creating processing centres along the north African littoral – sounds a lot like replicating the Libyan holding camps that have become notorious for abuses. Another problem: nobody seems to have asked Egypt, Tunisia, Algeria or Morocco whether they are willing to be re-colonised as dumping grounds for Europe’s problems.

Sebastian Kurz, Austria’s rightwing chancellor, goes further, talking about military “secure zones” in north Africa. His ministerial colleague, Herbert Kickl, wants to “concentrate” migrants in one far-off place. Like Salvini’s ideas about rounding up and expelling Roma people, such talk carries disturbing echoes of the 1930s. Austria will hold the EU council of ministers chair from next month, from where it can push its agenda.

The recent pan-European surge in nationalist, populist and xenophobic political forces forms the intractable backdrop to the immigration crisis. Similarly, Trump won in 2016 on a wave of demagoguery that exploited Middle America’s fears. Phobias about foreigners, mixed with old-fashioned racism and concerns over terrorism, were the genesis of his Mexican border wall and his ban on citizens from Muslim countries. Yet, like many European politicians, Trump ignored the root causes of problematic migration – and, in many instances, the west’s culpability.

American wars in the Middle East, notably in Afghanistan, Iraq and Libya; the collective failure to halt the Syrian, Yemeni, South Sudanese and Somali conflicts; and the tolerance shown to repressive, undemocratic regimes in Eritrea and Egypt have all stoked the crisis.

Add the ever-widening north-south wealth gap, western indifference to the economic plight of sub-Saharan African and west Asian countries, the disproportionate impact of climate change and environmental pollution, and the chronic insecurity of lives lived in impoverished, unstable societies, and it is not hard to see why large numbers of people would prefer to move to Michigan or Magdeburg.

In the specific case of the US southern border, much of the migration from Mexico and Central America is an attempt to escape murderous narco-wars involving gangs feeding off massive US demand for illegal drugs, something Trump has done little to curb.

Unusually among top politicians, Merkel grasps the connections and has urged a more holistic approach. She was instrumental in creating the EU’s €4.3bn emergency trust fund for Africa, dedicated to fighting “the root causes of irregular migration” (and thereby curbing it) through investing in jobs, education, training and good governance in countries of origin.

But recent research shows three states that together are the biggest source of asylum seekers – Nigeria, Somalia and Eritrea – received less EU money than more stable, better-off countries such as Ethiopia. The trust has also been criticised for spending too much on preventing migration and tighter border controls, rather than improving lives.

More time bombs are ticking. In the absence of agreed, joined-up solutions, the overall problem is expanding exponentially. According to the UN, wars, violence and persecution uprooted 68.5 million people last year – an all-time record.