Haile Selassie threatened to seize Djibouti by force if France withdrew.

Evidence

Speaking to a large crowd in Hargeisa’s Independence Garden, he reassured the people that their government’s stand was courageous and firm. His main points were … [t]he Ethiopian threat[:] … a) Emperor Haile Selassie has said he will take over Djibouti by force if the French leave. — Abdi Ismail Samatar, Africa’s First Democrats, 915