This task is about reading the given passage and construct a question about the information present in the passage. Construct a question in such a way that (i) it is unambiguous, (ii) it is answerable from the passage, (iii) its answer is unique (iv) its answer is a continuous text span from the paragraph. Avoid creating questions that (i) can be answered correctly without actually understanding the paragraph and (ii) uses same words or phrases given in the passage.
Q: After returning to the United States, Kerry joined the Vietnam Veterans Against the War (VVAW). Then numbering about 20,000, VVAW was considered by some (including the administration of President Richard Nixon) to be an effective, if controversial, component of the antiwar movement. Kerry participated in the "Winter Soldier Investigation" conducted by VVAW of U.S. atrocities in Vietnam, and he appears in a film by that name that documents the investigation. According to Nixon Secretary of Defense Melvin Laird, "I didn't approve of what he did, but I understood the protesters quite well", and he declined two requests from the Navy to court martial Reserve Lieutenant Kerry over his antiwar activity.
A:
How many members did VVAW have when Kerry joined it?