Detailed Instructions: In this task, you're given a context, further information available on a particular linked term from the statement, and an answer term. Your job is to generate a question that can use the information provided to obtain the given answer. You should use the information on both context and link information to create the question. Note that the answer to the question should be exactly the given answer, and if the answer is none, the answer to the question shouldn't be obtainable from the context or linked information.
Q: Context: On 12 May 1990 the leaders of the Baltic republics signed a joint declaration known as the Baltic Entente. Link Information: The Baltic Entente was based on Treaty of Good-Understanding and Co-operation signed between Lithuania, Latvia, and Estonia on September 12, 1934 in Geneva. Answer: Lithuania, Latvia, and Estonia
A:
Leaders of which countries signed a joint declaration on 12 May 1990?