Google's irate missive against Apple and Microsoft yesterday was met with a quick reply from Microsoft, who suggested on Twitter that Google was being disingenuous.

Microsoft said Google had declined its offer to jointly bid on a set of patents owned by Novell, implying Google was being uncooperative, not the object of a purposeful campaign to use patents to hamper its Android operating system with licensing fees and lawsuits.

But the tit for tat between the two tech giants took another turn yesterday, when Google confirmed that it had turned down an offer from Microsoft on the Novell patents, but said it had a good reason for doing so.

"A joint acquisition of the Novell patents that gave all parties a license would have eliminated any protection these patents could offer to Android against attacks from Microsoft and its bidding partners," Google chief legal officer David Drummond said in a Thursday afternoon post on the company's official blog. "Making sure that we would be unable to assert these patents to defend Android — and having us pay for the privilege — must have seemed like an ingenious strategy to them. We didn't fall for it."

Patent experts cited by The New York Times seemed to support Google's explanation, saying joint agreements on patents could do more harm than good unless all the owners of the patents agree on how to license them.

According to the publication, "if Google and Microsoft jointly own a patent and a third party wants to sue Google, Microsoft could theoretically license that patent to the third party and Google would lose its protection from that patent."

In a series of Twitter posts, Microsoft spokesman Frank Shaw responded to Google, saying, "We offered Google the opportunity to bid with us to buy the Novell patents; they said no. Why? BECAUSE they wanted to buy something that they could use to assert against someone else. SO partnering with others & reducing patent liability across industry is not something they wanted to help do."

The acquisition of the Novell patents by Microsoft and a group of other tech companies including Oracle, Apple and EMC attracted the attention of the Justice Department, which ordered the group to license the patents to the open source community "to protect competition and innovation in the open source software community."

Specifically, the DOJ said that the original terms of the deal, which would not have required Microsoft, Oracle, Apple and EMC to allow other companies access to the patents, "would jeopardize the ability of open source software, such as Linux, to continue to innovate and compete in the development and distribution of server, desktop, and mobile operating systems, middleware, and virtualization products."

Google recently lost an auction of Nortel's patents on wireless technologies by a similar cadre of tech companies including Apple and Microsoft, which together threw in $4.5 billion for the vendor's intellectual property portfolio.

Google claims Apple and Microsoft are using the patents to make Android smartphones more expensive by imposing high licensing fees on patents used by the operating system, as well as plaguing manufacturers of Android smartphones with superfluous lawsuits over what it calls "bogus" patents.