Russia's Foreign Ministry said it would issue a “harsh and painful” response to the expulsion of its diplomats in Budapest. Budapest says the expulsions are necessary to protect security and sovereignty after years of comparatively close ties between Hungary and Russia. Key points and original sources are listed below.

• Russia's Foreign Ministry said it would issue a “harsh and painful” response to the expulsion of its diplomats in Budapest.S1

• Budapest says the expulsions are necessary to protect security and sovereignty after years of comparatively close ties between Hungary and Russia.S2

• Hungary has ordered 10 Russian diplomats to leave the country over activities deemed unacceptableS3S4