Iran has invited Boeing to take part in the investigation into a Ukrainian jetliner that crashed earlier this week at a time of soaring tensions between Washington and Tehran, killing all 176 people on board, state media reported Friday.

The move came after Western leaders said the plane appeared to have been unintentionally hit by a surface-to-air missile hours after Iran launched ballistic missiles at two US bases in Iraq to avenge the killing of its top general in an American airstrike.

The ballistic missile attack on the bases caused no casualties, raising hopes that the standoff over the killing of Gen Qasem Soleimani would end relatively peacefully. But Iran has sent mixed signals over whether its retaliation is complete.

Foreign Ministry spokesman as saying Iran “has invited both Ukraine and the Boeing company to participate in the investigations.

The spokesman, Abbas Mousavi, said it will also welcome experts from other countries’ whose citizens died in the crash.

US, Canadian and British officials said it is “highly likely” that Iran shot down the Boeing 737 that crashed near Tehran late on Tuesday.

US officials said the jetliner might have been mistakenly identified as a threat.

Canadian Prime Minister Justin Trudeau, whose country lost at least 63 citizens in the downing, said we have intelligence from multiple sources including our allies and our own intelligence.

“The evidence indicates that the plane was shot down by an Iranian surface-to-air missile,” he said.

UK Prime Minister Boris Johnson and Australian Prime Minister Scott Morrison offered similar statements.

Morrison also said it appeared to be a mistake. “All of the intelligence as presented to us today does not suggest an intentional act,” he said.

Mousavi said Iran asks Canada’s prime minister and any other government to “provide any information they have to the investigation committee”.

Iranian officials have ruled out a missile strike, and initially said the plane appeared to have crashed because of technical difficulties.

A preliminary Iranian investigative report released on Thursday said that the airliner pilots never made a radio call for help and that the aircraft was trying to turn back for the airport when the burning plane went down.

The Iranian report suggested that a sudden emergency struck the Boeing 737, operated by Ukrainian International Airlines, just minutes after taking off from Imam Khomeini International Airport in Tehran early on Wednesday.

Before the US assessment, Iran’s state-run IRNA news agency quoted Hasan Rezaeifa, the head of the civil aviation accident investigation commission, claiming that the topics of rocket, missile or anti-aircraft system is ruled out.

The US accident investigator, the National Transportation Safety Board, is talking to the State Department and the Treasury Department about traveling to Iran to inspect the US-built aircraft and working with Iranian authorities despite US economic sanctions against that country.

In a statement on Thursday the NTSB said it continues to monitor the situation surrounding the crash and evaluate its level of participation in the investigation.

US officials have expressed concerned about sending employees to Iran because of the heightened tensions.