America’s $42bn foreign assistance programme is facing “unprecedented” disruption a year into Donald Trump’s presidency, according to former top officials who have described the White House’s approach as deeply counterproductive and putting lives at risk.

Scott Morris, a former senior US Treasury official now with the Center for Global Development in Washington, told the Observer: “One of the negative things to watch for is how seriously this administration seeks to operationalise a policy of ‘aid to friends’ across the board.

“I don’t think there is any reason to rule out the seriousness of that threat, in the absence of any tempering comments in this administration.”

In his State of the Union address last month, Trump reiterated plans to tie foreign aid to support for US foreign policy. Officials’ concerns come amid mounting fears that the White House Office of Management and Budget will renew pressure – blocked by Congress last year – for “draconian” cuts to the US foreign assistance budget.

Morris said his fears had been reinforced by the fact that the Trump administration has already made good on threats to cut aid to UNRWA – the United Nations agency that deals with Palestinian refugees – and curtail security assistance to Pakistan, with fears that other cuts may be in the pipeline. “The policy agenda of this administration continues to be hostile to the uses of aid and the rationale that has defined it for decades,” added Morris.

Questions over the future of the US aid budget, and what the purpose of American aid should be, have also been injected into the wider ideological struggle over America’s global role, including the fear that an isolationist Trump is leading a wide-ranging US withdrawal from international institutions.

All of this has led some to wonder whether the postwar vision of a US aid policy – articulated by John F Kennedy to Congress in 1961 as being “a wise leader and good neighbour in the interdependent community of free nations” – can survive a Trump presidency whose imperative is to “stop sending foreign aid to countries that hate us”.

Those anxieties were stoked again by Trump’s threat to cut aid to “dozens of countries” that voted in opposition to his decision to recognise Jerusalem as the capital of Israel – repeated in his State of the Union speech.

Morris says he sees “rays of hope” in some areas – for example, the bipartisan Congressional resistance to last year’s calls for swingeing cuts in the aid budget, and the public positions taken by Mark Green, the head of USAid. Nonetheless he is deeply concerned over the trajectory for US foreign assistance under Trump.

Like others, he argues that, although the initial calls for cuts of 30% in aid budgets may have been avoided last year, deep reductions may still be on the agenda, amid a continuing lack of clarity over what the administration hopes to achieve.

“I think what is driving this is a president who has embraced the negative politics of foreign aid,” he said, pointing to polls that suggest a slim majority of Americans believe too much is spent on aid – even though most voters also think America spends more than it actually does.

“When you don’t have a clearly defined framework policy, and it reverts to the crudest vilification of the assistance programme, then the starting point [for officials] is simply the need to deliver deep cuts,” he said.

Many of Morris’s concerns are shared by James Dobbins, a former assistant secretary of state in both Republican and Democratic administrations and now an analyst at the Rand Corporation thinktank.

Trump’s “aid for friends” policy, Dobbins said, was “indicative of this president’s transactional view of the world. The reality is the US provides foreign aid because it has been determined by successive administrations to be in our interest. To threaten to cut it off, in a tit-for-tat approach, is to cut off your nose to spite your face.”

Although Dobbins acknowledges that political conditions were attached to the Marshall Plan, which helped to rebuild Europe after the second world war, in other cases, he says, that is an approach that has usually backfired.

“Pakistan is a good example. Congress passed legislation in the 1990s making aid conditional on dropping its nuclear weapons programme. Pakistan then rejected that aid, and went ahead with its weapons programme.

“Clearly, that effort did not have the desired impact.”

“The talk of conditionality over aid that we are hearing from the Trump administration is foolish and doesn’t work,” said John Norris of the Sustainable Security and Peacebuilding Initiative at the Center for American Progress, who served on Barack Obama’s Global Development Council.

“It is lousy diplomacy that ends up isolating us. It takes us away from the idea that development is a long-term venture that takes time and is inherently the right thing to do.”

Although Norris commends the bipartisan pushback from Congress on budget cuts, he argues that the continued threat is already having an impact on US aid programmes, as organisations have been warned to plan for reductions.

“People are still being told they need to plan as if there is going to be a 30% cut and contingency-plan accordingly. If you are a big NGO, that is fine, but it is much tougher for smaller programmes. If you are employing 20, 60, 100 people, the threat of a three-month funding gap is disastrous.”

Finally, there is the question of Trump’s chaotic approach. “The unfortunate part of all this – as we have seen on the military side already – is that [Trump] will cough something out on Twitter and then send everyone scrambling to make policy fit,” adds Norris. “In international development, the people likely to suffer most are those with the least agency and power, the world’s poorest on whom these callously made decisions have enormous impact” – including, he fears, on increased infant and women’s mortality.

“There are all kinds of legitimate complaints about how aid works, but even the most embittered economists know aid saves lives. We know the baseline of misery will increase significantly. Even though our systems are resilient, there will be a lot of explaining required around the world afterwards about what happened during our ‘episode’.”