Robert Mueller, the former special counsel whose investigation into alleged Russian interference in the 2016 US election defined much of Donald Trump’s first term in office, has died. He was 81.

The cause was not immediately known. CBS News, the BBC US partner, confirmed his death.

“With deep sadness, we are sharing the news that Bob passed away” on Friday night, the family said to the AP in a statement. “His family asks that their privacy be respected.”

Mueller previously led the Federal Bureau of Investigation (FBI) from 2001 to 2013, taking the office just days before the 11 September 2001 terror attacks. He is credited with reshaping the FBI into a modern counterterrorism agency.

Mueller is survived by his wife of nearly 60 years, Ann Cabell Standish, their two daughters, and three grandchildren.

Mueller’s special counsel inquiry put Trump’s 2016 campaign under a microscope, drawing harsh criticism from the president.

The president on Saturday wrote on Truth Social: “I’m glad he’s dead. He can no longer hurt innocent people!”

Mueller’s former employers and colleagues praised him as a longtime public servant.

“A great American died today, one I was lucky enough to learn from and stand beside,” wrote former FBI director James Comey, who succeeded Mueller at the agency and whose abrupt firing by Trump led to the Mueller investigation.

In a statement, a spokesman for his former law firm, WilmerHale, called Mueller an “extraordinary leader and public servant and a person of the greatest integrity”.

Mueller was born in 1944. After studying politics at Princeton University, he joined the Marines and deployed to Vietnam in 1968.

As a lieutenant, Mueller led a platoon of troops, was wounded twice in battle, and was awarded numerous commendations, including the Bronze Star for valor and a Purple Heart.

After returning from the war he went to the University of Virginia, where he studied law and graduated in 1973.

In August 2001, Mueller was unanimously confirmed as FBI director by the Senate, and he served at the agency for more than a decade.

Mueller retired from the FBI in 2013, after serving under both a Republican president, George W Bush, and a Democrat, Barack Obama.

But four years later, Mueller found himself at the center of a political maelstrom that consumed Washingtonan would later define his legacy.

His investigation into Russian attempts to influence the 2016 presidential election – and the potential involvement of Trump and his campaign – were a near daily source of intrigue and speculation for nearly two years, from May 2017 to March 2019.

The court filings of his special counsel’s office were meticulously picked apart, with each new revelation a potential bombshell that could, depending on one’s perspective, bring down a president or destroy a nation.

Trump condemed Mueller’s inquiry as a “witch hunt” and a “hoax”, and viewed him as one of his greatest political adversaries. Trump frequently said there had been “no collusion” between his campaign and Russia.

During the investigation, Mueller’s team scrutinised Russia’s actions as well as several of Trump’s top campaign staff and allies. Despite his work frequently making headlines, Mueller himself rarely spoke publicly.

The investigation resulted in multiple indictments and plea deals with former Trump campaign manager Paul Manafort, as well as national security advisor Michael Flynn.

In the end, the 448-page “Mueller report” was thorough but ultimately inconclusive. It found that Russia interfered in the 2016 election in a “sweeping and systemic fashion”, but did not establish that members of the Trump campaign conspired or coordinated in these activities.

His findings noted: “while this report does not conclude that the president committed a crime, it also does not exonerate him.

In February 2021, Mueller sat for a rare interview with MSNBC to recount key moments in his decades-long career.

Asked why he agreed to oversee something as politically daunting as his Russia investigation, he said: “I found that I’ve gotten tremendous enjoyment out of public service. And I find it hard to turn down a challenging assignment.”

The foreign secretary has said the UK will continue to provide defensive support against “reckless Iranian threats” but insisted it would not be drawn into a wider conflict in the Middle East.

Yvette Cooper was speaking after it emerged Tehran had targeted the joint US-UK military base in the Chagos Islands, with reports of two ballistic missiles being fired at the island of Diego Garcia.

Supporting UK interests included taking defensive action against ballistic missile threats, she added.

Cooper said the UK recognised “Iran’s escalating threats to international shipping as well as their threats to our Gulf partners” and she reiterated it wanted to see a swift end to the conflict.

The Wall Street Journal and CNNreportedon ballistic missiles being fired at Diego Garcia, citing unnamed US officials, but said that neither weapon reached its target.

One of themissiles firedreportedly failed in flight, while the other was intercepted by a US warship. The BBC understands the reports are accurate. There are doubts whether Iran has missiles which are capable of reaching Diego Garcia, which is about 2,350 miles from Iran.

The BBC understands the missiles were fired by Iran sometime during the period late on Thursday night into Friday morning.

Initial information had been limited only to the fact the incident had happened before Friday afternoon when ministers met in London to discuss the war and the UK agreed to let the US use British military bases to hit Iranian sites targeting shipping through the Strait of Hormuz.

The US military has declined to comment on the incident.

Meanwhile the foreign secretary reiterated the UK’s position in her interview on Saturday.

“As the prime minister has made clear we will provide defensive support against these reckless Iranian threats but we have not been – and we continue not to be – involved in offensive action,” she said.

She continued: “We will not be drawn into a wider conflict because we think we need to see as swift as possible resolution in the UK national interest but also to support regional stability”.

The airbase on Diego Garcia is strategically located, capable of accommodating long-range bombers and has been used as a launchpad for operations in the Middle East for years.

Its use in US strikes on Iran has been limited as the UK government has only allowed British airbases to be used for strikes on sites targeting UK interests and allies in the region.

The government announced on Friday that it had agreed to allow the US to use British bases to launch strikes on Iranian sites targeting the Strait of Hormuz.

On Saturday Sir Keir Starmer spoke to the Cypriot president reiterating that RAF Akrotiri would not be one of the bases used by the US to target Iranian missile sites.

Tehran launched several unmanned drones at the military base in Cyprus, one of which struck its runway causing “minimal” damage earlier this month,

Iran’s Foreign Minister Abbas Araghchi said this week that the UK’s participation was “putting British lives in danger” and that Iran would “exercise its right to self-defence”.

The Liberal Democrats and the Greens have called for a vote in the Commons on allowing the US to use UK bases, while Conservative leader Kemi Badenoch calling it the “mother of all U-turns”.

Sir Keir Starmer will separately hold a Cobra meeting next week on plans to help mitigate the impact of the war on the cost of living. The International Energy Agency expects the disruption to oil supply to affect wider energy markets.

Cooper said on Saturday Iran’s “reckless attempt to hijack the global economy” was affecting the cost of living and supporting families was the government’s “top priority”.

She cited how the energy cap would “lower energy bills in the spring”, while the government had announced support to help offset the rise in the price of heating oil.

British control

The UK government has agreed to cede sovereignty of the Chagos Islands to Mauritius and lease back the base on Diego Garcia.

Sir Keir has previously insisted the deal was necessary to protect the continued operation of the base, amid previous attempts from Mauritius to dispute the legality of British sovereignty over the islands.

The Chagos Islands have been under British control since 1814. They were administered from Mauritius, another British colony.

In 1965, the Chagos Islands were made a British overseas territory in their own right, ahead of Mauritius gaining independence, and the UK government paid Mauritius a £3m grant in compensation.