A 24-year-old man has been charged over an alleged plan to carry out a terror attack on American military personnel in Britain.
Junead Ahmed Khan is also accused, along with his uncle, Shazib Ahmed Khan, 22, of planning to travel to Syria to join Islamic State (IS) - also known as Isil.
The men, both from Luton, will appear at Wesminster Magistrates' Court in London later.
Deborah Walsh, deputy head of counter terrorism at the Crown Prosecution Service, said the charges follow an investigation by Scotland Yard's counter-terrorism command.
She said: "We have concluded that there is sufficient evidence and it is in the public interest to charge Junead Khan and Shazib Khan with the intention of committing acts of terrorism.
"It is alleged that Junead Khan and Shazib Khan had been planning on travelling to Syria to join the proscribed organisation Islamic State in Levant (Isil).
"It is further alleged that Junead Khan was planning a terrorist attack on US military personnel in the UK and he has been charged with an additional terrorism offence to reflect this."
Both men are charged under section 5(1)(a) of the Terrorism Act 2006.
It states that "with the intention of committing acts of terrorism" they "engaged in conduct in preparation for giving effect to that intention".
The count relating to both men covers a period between August 1 2014, and May 10 2015.
Junead Ahmed Khan faces an additional charge dating between May 10 2015 and July 14 2015.
The two men were arrested a week ago.
Another man, in his 30s, was also detained. He was released without charge last night.
Searches were carried out at two addresses in the Luton area. Scotland Yard said the activity was part of an ongoing investigation into alleged Islamist-related terrorism.