Four men have pleaded guilty to engaging in conduct in preparation of terrorist acts.
Zahid Iqbal, Mohammed Sharfaraz Ahmed, Umar Arshad and Syed Farhan Hussain admitted facilitating, planning and encouraging travel overseas contrary to Section 5 of Terrorism Act 2006.
The men were arrested following a series of anti-terror raids in Luton, Beds, last year.
All four, aged between 21 and 31, were due to stand trial next month.
Woolwich Crown Court heard that Iqbal, of Bishopscote Road, Arshad, Hussain and Ahmed downloaded computer files containing practical instruction for an attack.
The men purchased survival equipment and collected funds for terrorist purposes. The offences took place between January 2011 and April last year.
Following their guilty plea, further charges of possessing documents including the al-Qaeda magazine Inspire will be ordered to lie on file.
The men were charged with possessing copies of a manual written by Anwar Al Awlaki, a radical American Muslim cleric of Yemeni descent who was killed last year in a US drone strike, called 44 Ways to Support Jihad.
Ahmed, of Maidenhall Road, and Arshad, of Crawley Road, were also said to have held a copy of 21 Techniques of Silent Killing, while the latter was claimed to have been in possession of The Al Qaeda Manual.
Hussain, of Cornel Close, was alleged to have possessed The Book of Jihad and a copy of The Explosives Course 2.
Mr Justice Wilkie adjourned the case for sentencing on 15 April.