Sam Cohen the father of the neutron bomb has written that red mercury can be used to make baseball sized neutron bombs for suitcase weapons. That is his science and not his speculation. Cohen also reported that red mercury had been found in Iraq by UN weapons inspectors
First off: has Sam Cohen built a working neutron bomb using "Red Mercury?" (As in, the alleged "red mercury antimonide" compound?) Betcha the answer is "no." The problem is that until someone demonstrates a working "red mercury" bomb, it's speculation. Apparently, a LOT of countries have been scammed by the Russian Mafiya peddling this BS tale.
Second, it seems that "Red Mercury" was the Soviet codename for Lithium Deuteride, which is used to provide the fusion fuel for thermonuclear weapons. Lithium Deuteride does NOT make neutron bombs baseball-sized. Sorry.