Donald Trump’s ambition to strike a sweeping peace deal to end the war in Ukraine will ultimately be “dashed” because Vladimir Putin cannot be trusted to stick to any agreement, according to former US National Security Adviser Lieutenant General HR McMaster. At best, the US President may succeed in freezing the conflict along current front lines – but any lasting peace will require sustained military pressure, not just negotiation, warned the ex-military commander.

Lt Gen McMaster was speaking to the Foreign Press Association as he promoted his new book, At War With Ourselves: My Tour of Duty in the Trump White House. Arguing that Mr Trump was “overconfident” in his belief that he could do business with hostile regimes such as Russia, he added: “There’s no agreement with Russia that’s going to lead to some kind of enduring peace.” Citing broken commitments such as the 1994 Budapest Memorandum – in which Ukraine gave up its nuclear arsenal in exchange for security assurances – and the Minsk agreements of 2014 and 2015, Lt Gen McMaster said Russia had a long record of violating its promises.

He added: “The Putin regime…will not moderate their aspiration to restore the Russian Empire.”

As such, he warned that aspirations for a quick-fix resolution to the war via a grand deal between Mr Trump and Mr Putin are destined to collapse.

He stressed: “Those hopes will be dashed.”

Lt Gen McMaster was also critical of how both Mr Trump and former President Joe Biden handled Ukraine.

While praising Mr Trump’s achievements in other areas, including confronting China, he said his treatment of allies had sometimes been counterproductive.

He explained: “President Trump insulted allies, threatened to leave NATO, created doubts about the US commitment to mutual defence – and that did embolden Putin.”

Of Mr Biden’s handling of the early stages of the conflict, he said: “There was a failure of deterrence. When the Biden administration came in, they suspended lethal assistance to Ukraine, and they pulled out US advisers. That communicated weakness.”

However, Lt Gen McMaster suggested that Mr Trump may now be forced by events to adopt a more robust position.

He said: “America will back itself into a strategy that I think is appropriate, which is that peace can only be guaranteed through strength.”

Lt Gen McMaster also spoke in favour of economic deregulation, energy independence, and improved transatlantic cooperation – particularly with Germany, which he said was now starting to take more responsibility for European defence.

His remarks come at a time of renewed speculation over a possible ceasefire between Russia and Ukraine.

According to reports in the Financial Times, Mr Putin is signalling a willingness to agree a ceasefire along current front lines – but only if Ukraine and its allies accept Russia’s territorial gains.

Kyiv has rejected that position, insisting on the restoration of its 1991 borders, including Crimea.

Meanwhile, Ukraine’s President Volodymyr Zelensky has warned that a premature ceasefire would allow Russia to regroup and attack again in future.

Tensions remain high as Russia prepares to hold its annual Victory Day parade on May 9, marking the Soviet Union’s victory over Nazi Germany.

The Kremlin has also declared a unilateral three-day ceasefire – ostensibly for humanitarian reasons – but Ukrainian officials say they remain sceptical.

The war, now in its third year, continues to grind on, with heavy casualties on both sides. According to the UK’s Ministry of Defence, Russia has suffered more than 900,000 military casualties – including over 200,000 killed – since the full-scale invasion began in February 2022.

Ukrainian sources suggest the death toll may be even higher, with over 427,000 Russian casualties reported in 2024 alone.

Lt Gen McMaster said: “We have to recognise the nature of these regimes. You can’t negotiate with them from a position of weakness.”

Putin would never stop of his own volition, Lt Gen McMaster stressed, adding: “He will only stop when he is stopped.”