Hopes for a deal to end the war in the Middle East were easing on Tuesday, as few signs emerged that the U.S. and Iran were close to breaking a protracted impasse.

Dampening sentiment were comments from U.S. President Donald Trump, who told reporters on Monday that a fragile ceasefire between Washington and Tehran was on “massive life support.”

Earlier, Trump rebuffed Iran’s response to an American proposal to end the fighting, describing it is as “unacceptable” and later as a “piece of garbage.”

Tehran, for its part, said that its counteroffer was “generous and responsible,” with most of the focus on reopening the Strait of Hormuz. The narrow conduit off of Iran’s southern coast has been effectively shuttered for weeks, crimping global oil supply flows and fueling fears of a global energy crisis.

At the same time, there were indications that brinkmanship was returning to the conflict. Trump has grown impatient with the continued closure of the Strait of Hormuz, as well as what he sees as a fractured Iranian leadership that is preventing them from making headway in nuclear talks, CNN reported, citing sources familiar with the matter. 

Some observers have suggested that Trump’s much-anticipated upcoming trip to China and meeting with Chinese President Xi Jinping could help crack the impasse. The theory goes that China, a major importer of Iranian crude, may act as a guarantor of any long-term peace agreement.

“Many people seem to be holding out hope that the Trump-Xi summit later this week in Beijing could yield a breakthrough on Iran […] but this might just be wishful thinking,” analysts at Vital Knowledge said in a note.

“We continue to feel that Trump is extremely reluctant to escalate militarily, but this is now the consensus view, which puts the White House in a dangerous position as its kinetic credibility erodes.”

Oil prices resumed their march higher. Brent crude futures, the global benchmark, were last higher by 2.0% at $106.30 a barrel, well above pre-war levels of around $70 a barrel. This uptick has, in turn, fed worries over a surge in inflation and led to expectations that central banks will react by hiking interest rates.