One of the men is said to have reconnoitred the Jyllands-Posten office
Two men from Chicago have been charged with plotting overseas attacks, including on the Danish newspaper which published cartoons about Islam.
David Coleman Headley, 49, and Tahawwur Hussain Rana, 48, were arrested earlier this month.
US prosecutors say Mr Headley travelled to Denmark twice to plan an attack on the Jyllands-Posten newspaper offices.
They say he was infuriated by the paper's publication of cartoons of the Prophet Mohammed in 2006.
The cartoons sparked angry, sometimes violent protests from Muslims in several countries.
In a statement, the US justice department said it had uncovered "a serious plot against overseas targets by two Chicago-based men working with Pakistani-based terrorist organisations".
Mr Headley, who changed his name from Daood Gilani in 2006, was arrested on 3 October as he was about to travel to Pakistan following a joint investigation by the FBI and the Danish Security and Intelligence Service (Pet).
He has been charged with "conspiracy to commit terrorist acts involving murder and maiming" outside the US and also with conspiracy to provide material support for the attack. If found guilty he faces up to life in jail.
'Mickey Mouse project'
Prosecutors allege he visited the Copenhagen and Arhus offices of the Jyllands-Posten newspaper for surveillance purposes.
They say he dubbed the planned attacks on the newspaper "the Mickey Mouse project".
The charge sheet alleges he also travelled to Pakistan to meet members of the Islamic militant group Lashkar-e-Taiba, and also made contact with Harakat-ul Jihad Islami, a Pakistani-based group with links to al-Qaeda.
Mr Rana, who officials say is a native of Pakistan and citizen of Canada, was arrested at his home on 18 October.
He is alleged to have helped Mr Headley plan and finance the attacks, and faces up to 15 years in jail.
Mr Rana's attorney, Patrick Blegen, said his client was "a well respected businessman in the Chicagoland community".
"He adamantly denies the charges and eagerly awaits his opportunity to contest them in court and to clear his and his family's name," Mr Blegen said, in comments quoted by AP news agency.
"We would ask that the community respect the fact that these are merely allegations and not proof."
AP quoted Mr Headley's lawyer as saying his client would make no comment.