Samsung has been chasing SanDisk trying to get it to accept an acquisition offer of $26 a share cash, $5.85 billion total, and was frustrated enough with the American flash company’s negative response to go public with its unsolicited, potentially industry-altering, proposition late this evening and publish its letter to the SanDisk board.

Said letter, over the signature of Samsung CEO and vice-chairman Yoon-Woo Lee, says that SanDisk, which is on the ropes because of oversupply, slammed the door on Samsung’s fingers yesterday after four months of discussions and meetings and, according to Samsung, “continues to cling to unrealistic expectations on both its standalone market value and an appropriate merger price.”

Samsung naturally feels that its offer is “full and fair” and “constitutes a very substantial premium” of 94% over SanDisk’s closing price on September 4, the day before word of their discussions leaked to the press. Samsung points out that it’s still an 80% premium to SanDisk’s closing price yesterday.

Apparently SanDisk wants $56, its 52-week high, and may have hopes that Toshiba, whose corporate senior vice-president expressed interest today, will swoop in and beat out Samsung.

Samsung + SanDisk, a combination that would own half the market, apparently making it a regulatory issue, would throw a monkey wrench into Toshiba’s plans to grab share by doubling output.

Anyway, in its hardball response, Samsung writes, “The world has changed dramatically in the past 52 weeks as can be seen from SanDisk’s own disappointing results. Consumer spending and the overall economic situation have been getting worse. It will take the NAND flash market quite a time of time to recover. Notwithstanding the current market condition, to stay competitive, SanDisk will need to fund critical investment and development over the next several months – costing cutting will not suffice. Our offer insulates your shareholders from the risk of market conditions that have severely deteriorated and are expected to remain challenging….We strongly believe that there is a significant execution risk of achieving any standalone plan.”