Britain is seeking to reassure Gibraltar that it will protect the territory’s interests in forthcoming talks on exiting the European Union.

Foreign Secretary Boris Johnson talked with Gibraltar’s chief minister, Fabian Picardo, on Friday to assure him of the U.K.’s support after the EU suggested Spain would have a veto over the territory’s future relationship with the trading bloc.

After the conversation, Johnson tweeted- “As ever, the U.K. remains implacable and rock-like in our support for Gibraltar.”

Gibraltar says Spain is using the U.K.’s impending departure from the EU to force negotiations on the status of Gibraltar, a territory Spain has been trying to get back from Britain for 300 years.