In an interview with Fox News channel's 'Sunday Morning Futures', Mr Trump was asked about his controversial decision to pause support for Kyiv as it fends off Russia's full-scale invasion, Sky News reports.
Mr Trump, who had a disastrous meeting with Mr Zelenskyy at the White House last week, was asked about a warning from Polish President Andrzej Duda "that without American support, Ukraine will not survive".
Asked if he was "comfortable" with that outcome, the US president said: "Well, it may not survive anyway.
"But we have some weaknesses with Russia. You know, it takes two," Mr Trump added.
It comes as Mr Zelenskyy will visit Saudi Arabia for a Monday meeting with Crown Prince Mohammed bin Salman, while Ukrainian diplomatic and military representatives will meet with a US delegation on Tuesday.
Mr Trump's latest remarks come amid global concern over the souring relationship between Ukraine and the US, which alongside the EU has been Kyiv's main backer in its defence against Russia's three-year land, air and sea invasion.
The US paused military aid and the sharing of intelligence with Ukraine this month after a meeting between Mr Trump and Mr Zelenskyy on 28 February descended into acrimony in front of the world's media.
