The Islamic State (ISIS) group on Sunday claimed responsibility for a suicide bombing this week that killed seven Jordanian soldiers on the Syrian border, the jihadist-linked news agency Amaq said in a statement on its website, according to AFP.
Quoting an unnamed source, it said Tuesday's attack against "the Jordanian-American base at Rokban in Jordan was carried out by an Islamic State fighter".
The blast, which also left 13 soldiers wounded, struck an area where thousands of Syrian refugees are stranded.
According to the Jordanian army, the suicide bomber set off from the makeshift Syrian refugee camp near the Rokban crossing in Jordan's remote northeast.
He then entered Jordanian territory through an opening used for humanitarian aid deliveries and blew himself up as he reached a military post, it added.
Following the attack, King Abdullah condemned it and said Jordan's armed forces would strike back.
"Jordan will respond with an iron fist against anyone who tries to tamper with its security and borders," he said.
"Such criminal acts will only increase our determination to confront terrorism and terror gangs that target army personnel who protect the security of the country and its borders."
Soon after, the army issued a statement declaring Jordan's desert regions that stretch northeast to Syria and east to Iraq "closed military zones".
"We will deal firmly with any vehicle of individual that moves in the area without (prior authorization) because they will be considered enemy targets," it warned.
Tuesday's bombing came two weeks after a gunman killed five Jordanian intelligence officers in a Palestinian refugee camp north of the capital.
A suspect was later arrested but details of the attack have been kept under a gag order while the investigation continues.
Jordan has in the past carried out air strikes targeting ISIS jihadists and hosts coalition troops on its territory.
Maaz al-Kassasbeh, a Jordanian fighter pilot, was captured by the jihadists when his plane went down in Syria in December 2014 and he was later burned alive in a cage.
In March, Jordan announced it had foiled an ISIS plot to carry out attacks in the kingdom in an operation that led to the deaths of seven jihadists.
AFP contributed to this report.