But four days after the ban on people travelling from Iran, Iraq, Libya, Somalia, Sudan, Syria and Yemen was announced, the embassy has issued a clarification which is more in-tune with the foreign secretary's statement in parliament.
This morning the embassy updated guidance on the executive order signed by Donald Trump on Friday night, clarifying that Britons who share dual nationality with countries on the list will be allowed into the US.
"Dual nationals of the United Kingdom and one of these countries are exempt from the Executive Order when travelling on a valid United Kingdom passport and US visa," it said.
The executive order states people travelling from, or who were born in, the seven nations listed will not be allowed to travel to the US for the next 120 days.
However, a statement from the foreign office released on Sunday night said: "If you are a dual citizen of one of those countries travelling to the US from OUTSIDE those countries then the order does not apply to you".
The confusion arose when, on Monday morning, the embassy published advice insisting it still applied. Then, later in the day, Johnson gave a statement to Parliament, insisting Britons were exempt.
"The general principle is that all British passport holders remain welcome to travel to the US," he said.
"We have received assurances from the US embassy that this executive order will make no difference to any British passport holder, irrespective of their country of birth or whether they hold another passport."
Today the embassy added: "We will announce any other changes affecting travellers to the United States as soon as that information is available."
Travel ban latest: The US embassy's statement in full
On January 27, 2017, President Trump signed an Executive Order temporarily suspending entry into the United States of foreign nationals from seven countries under section 212(f) of the Immigration and Nationality Act. Under the Executive Order, to allow for proper review and establishment of standards to prevent terrorist or criminal infiltration by foreign nationals, the Executive Order imposes on nationals of certain designated countries a 90-day bar on entry into the United States. This bar also includes a 90-day prohibition on visa issuance. These countries, as designated by Congress or the Secretary of Homeland Security, are: Iraq, Syria, Sudan, Iran, Somalia, Libya, and Yemen.
Beginning January 27, 2017, travelers who have nationality or dual nationality of one of these countries will not be permitted for 90 days to enter the United States or be issued an immigrant or nonimmigrant visa. Those nationals or dual nationals holding valid immigrant or nonimmigrant visas will not be permitted to enter the United States during this period. Visa interviews will generally not be scheduled for nationals of these countries during this period.
Dual nationals of the United Kingdom and one of these countries are exempt from the Executive Order when travelling on a valid United Kingdom passport and U.S. visa.
We will announce any other changes affecting travelers to the United States as soon as that information is available.