U.K. Prime Minister Boris Johnson was slow to ban travel to India, even as cases of a dangerous COVID-19 variant in the world’s second most populous country surged. Scientists and advisers now fear the U.K. has exposed its vulnerability, and the question is if the government machine can move fast enough when the next strain arrives.

Officials privately suspect Johnson’s team was reluctant to close the border to travelers from India for political reasons, with post-Brexit ties around the world high on the economic agenda. There were also concerns the country didn’t have the infrastructure in place to cope with the sheer number of people wanting to return to the U.K.

This week, ministers confirmed the variant discovered in India had taken hold in 86 separate parts of Britain, including areas of northwest England and Scotland’s biggest city, Glasgow. While Johnson says there’s no evidence so far that the arrival of the new strain will mean lockdown rules have to remain for longer, he has already warned a delay to lifting restrictions might be needed.