A journal found by investigators is said to praise Osama bin Laden
Prosecutors have charged the main suspect in the New York-New Jersey bombings with using a weapon of mass destruction.
Ahmad Khan Rahami will face allegations he planted a series of bombs in both states, including one which injured 31 people when it blew up on a bustling Manhattan street.
Investigators allege Rahami purchased bomb-making components on eBay - including ball bearings, citric acid and electronic igniters - before the attacks over the weekend.
Detectives also say they have recovered his hand-written journal, which accuses the US of slaughtering Islamist fighters across the Middle East - including in Afghanistan, Iraq and Syria.
The notebook is said to praise Osama bin Laden, who masterminded the September 11th terror attacks, and refer to terrorist leaders' instructions to "attack non-believers where they live".
Another excerpt reads: "The sounds of the bombs will be heard in the streets. Gunshots to your police. Death to your OPPRESSION."
Rahami also apparently wrote of his desire to be a martyr, and of concerns he would be caught before being able to carry out a suicide attack.
Rahami, who was born in Afghanistan, was captured on Monday after he was wounded in a gunfight in Linden, New Jersey.
He has already been charged with five counts of attempted murder in connection with that shootout.
After the 28-year-old was detained, he was pictured on a stretcher being taken into an ambulance, with a bloodied bandage on his right arm and moving his head from side to side with his eyes open.
Rahami remains in hospital with gunshot wounds to the leg, forearm and shoulder.
Although federal agents have tried to question him, US officials say he has not been co-operating.
The White House has said the bombing attacks over the weekend appear to be an act of terrorism.
An unexploded pressure-cooker bomb was found a few streets away from the shrapnel-packed device which exploded in Manhattan.
In New Jersey, a pipe bomb blew up in a park shortly before a charity run was due to begin on Saturday morning - and five explosive devices were discovered in a bin at a train station on Sunday night.
Prosecutors found Rahami's DNA and fingerprints at the scene of the Manhattan bombing, and have also discovered a clear CCTV image of the suspect from a camera near the site of the blast.
On Tuesday, it was revealed that Rahami had been previously reported to the FBI in 2014 by his father, but law enforcement officials found no "ties to terrorism" and dropped their investigation.