The US embassy in Oslo was hit by an explosion in the early hours of Sunday but no one was injured, police in the Norwegian capital said, adding the cause was not immediately known.

The blast occurred around 1am local time (0000 GMT) and caused only “minor material damage” to one of the building’s entrances, Oslo police said in a statement.

Investigators were examining the scene, while dogs, drones, and helicopters were involved in the search “for one or more potential perpetrators”, it said.

“Police view such incidents in public spaces as very serious, and are investigating the case with substantial resources and high priority.”

Police commander Michael Dellemyr told TV2 police would “not comment on anything related to the type of damage, what it is that has exploded and similar details, beyond the fact that there has been an explosion” because “it is very early in the investigation”.

He later told TV2 that police “have an idea of the cause”, adding: “It appears to us that this is an act carried out by someone.”

He said investigators were talking to witnesses, and TV2 reported that a bomb squad was at the scene.

Police said they were in contact with the embassy about the incident, and said several hours after the blast that the area around the building was considered “safe” for residents and passersby.

Police urged the public to report any tips or unusual observations from the area between midnight and 2am (2300 GMT and 0100 GMT).

Three ‘bangs’

US embassies have been placed on high alert in the Middle East over American military attacks in Iran and several have faced attacks as Tehran hits back at industrial and diplomatic targets.

But Dellemyr said there was no indication as yet that the incident at the embassy in Oslo was connected to the conflict.

“We’re not connecting it to the conflict. It’s far too early for that,” he told TV2.

Residents near the embassy described hearing the explosion.

A 16-year-old identified only as Edvard told TV2 that he was watching television when he heard the blast.

“My mother and I first thought it came from our house so we looked around a little, but then we saw the flashing lights outside the window and a ton of police,” he said.

“There were police dogs and drones and police with automatic weapons and helicopters in the air,” he said.

A group of three friends, meanwhile, told TV2 they were waiting for a taxi near the embassy when the explosion happened.

“We felt three ‘bangs’ that made the ground shake,” Kristian Wendelborg Einung said.

Once in their taxi, they drove past the scene and saw the street in front of the embassy covered in smoke.

“We arrived before the police. The blanket of smoke was very strange. It was like thick fog,” he said.

Iranian Foreign Minister Abbas Araghchi has blasted Washington’s reaction to President Masoud Pezeshkian’s extension of the hand of friendship to neighbors, saying that the gesture was almost immediately killed by US President Donald Trump.

“President Pezeshkian’s openness to de-escalation within our region — provided that our neighbors’ airspace, territory, and waters are not used to attack the Iranian People — was almost immediately killed by President Trump’s misinterpretation of our capabilities, determination and intent,” Araghchi wrote in a post published on his X account on Sunday.

He added that “If Mr. Trump seeks escalation, this is precisely what our Powerful Armed Forces have long been prepared for, and what he will get.”

Araghchi noted that responsibility for any intensification of Iran’s exercise of self-defense will lie squarely with the US administration.

The top Iranian diplomat highlighted that Trump’s week-long misadventure has already cost the US military $100 billion, in addition to the lives of young soldiers.

“When markets reopen, that cost will balloon, and directly be transferred to ordinary Americans at pumping stations,” he said.

Araghchi emphasized that Trump’s own National Intelligence Council, representing input from the 18 intelligence agencies of the US, determined that war on Iran is destined to fail.

The Iranian foreign minister went on to state that he had warned Trump’s envoys that war won’t improve Washington’s bargaining position, wondering whether such warnings were conveyed.

“The American People voted to end involvement in costly quagmires in the Middle East. Instead, they have ended up with an Administration that Netanyahu, after decades of failed attempts, finally managed to dupe into fighting Israel’s wars,” he said.

Araghchi finally described the ongoing US-Israeli aggression against Iran as “a war of choice pursued by a small cabal of ‘Israel Fighters,’ and ‘Israel First’ always means ‘America Last’.

The global positioning system (GPS) capabilities of cargo ships, oil tankers and other vessels stuck in the Middle East because of the widening war are likely worse than those in your cell phone.

Experts say this deficiency explains why since the start of US-Israeli strikes, the jamming of satellite navigation signals has left about 1,000 ships in the Gulf and the Gulf of Oman unable to determine their location, either momentarily or continuously.

Dimitris Ampatzidis, a senior risk and compliance analyst for the energy market intelligence firm Kpler, told AFP the number represents about half of the vessels in the area.

The vast majority of those ships are located off the United Arab Emirates and Oman.

A satellite navigation system is made up of a constellation of satellites that send signals with the time to Earth, allowing the receiver to determine its precise location.

Modern smartphones receive signals from four groups of satellites: the American, European (Galileo), Russian (GLONASS) and Chinese (BeiDou) Global Navigation Satellite Systems (GNSS).

Most cell phones now use two GPS frequency bands — one that is older and fainter, and a second that is newer and stronger.

But “many ships only listen to the original civilian GPS signal, which is called the L1 C/A signal. It’s the one that’s been around since the early 1990s for civilian use,” Todd Humphreys, an engineering professor at the University of Texas at Austin, told AFP.

Most ships are thus unable to rely on the BeiDou or Galileo systems in the event that a GPS is jammed.

The situation is even worse for airplanes, due to aviation regulations.

“You will not find any aircraft flying in the world today whose built-in GPS receiver is capable of tracking and interpreting signals other than the GPS L1 C/A. So it´s out of date by 15 years,” Humphreys said.

Spoofing

Jamming a GPS signal is “not that complicated,” said Katherine Dunn, the author of an upcoming book of the history of GPS, “Little Blue Dot.”

All one needs is “another radio transmitter that can broadcast on the same frequency, but louder,” she said, which creates “a wall of mush.”

Spoofing is more sophisticated — and more dangerous, affecting a ship’s Automatic Identification System, or AIS.

Every vessel transmits a message per second over a universal radio frequency that announces its identity, destination and position.

Spoofing manipulates that system, causing the affected ship to send a fake, or even nonsensical, location — meaning that ships could appear to be on land in Iran or the Emirates.

Clocks

Today, GPS signals are not just used to determine location; they also power onboard clocks, radar systems and speed logs, Dunn said.

So even if the ships off the Emirates or Kuwait were protected from drone fire and escorted through the Strait of Hormuz, navigating without a GPS would be perilous.

“Given the size of the ships, electronic assistance has become necessary to steer them,” said one merchant marine captain who has sailed on cargo ships around the world.

Crews must “resort to using 20th-century instruments — radar or visible landmarks,” he told AFP on condition of anonymity.

Defensive jamming

Signal jamming is undoubtedly being used both offensively and defensively. Gulf states are directing their systems towards their own shores to ward off Iran’s satellite-guided Shahed drones — at the cost, deemed acceptable, of disrupting their own lives.

Israel did the same thing in 2024, as did Iran after its 12 days of conflict with Israel last year.

“Even if their own air traffic or maritime traffic or their delivery drivers or their dating apps are affected by GPS jamming and spoofing, they’ll do it, just like Israel did. Israel did it for a year in 2024,” Humphreys said.

For air and sea navigation, start-ups are developing alternative technologies using Earth’s magnetic field or inertial navigation.

But for ships today, navigating without a GPS is still far in the future.