With the July 10 deadline for the P5+1 nuclear negotiations coming up rapidly, officials have reported yet another extension. Iran reported that the extension was for four additional days. Secretary of State John Kerry confirmed this, but did not provide details on the timetable, insisting only that the US “will not be rushed.”

This is an odd insistence, because all the indications from the past couple of weeks were that the July 10 deadline was more or less exclusively America’s idea, and US negotiators were the ones desperate to get a deal done. Over the past day, however, US demands appear to have shifted dramatically, preventing a likely deal and causing a new extension.

And it wouldn’t be a US statement on the ongoing talks if they didn’t involve a threat to walk away from negotiations outright, which Kerry once again said was possible, insisting that, despite his previous aversion to being rushed, the US wouldn’t let the talks continue forever.

That the US appears to have entirely torpedoed this deal in the last couple of days by overtly changing their demands is risky, and had Russian officials saying the new delays are the fault of Western nations, not Iran. It seems unlikely that the US could actually pull out from the talks without major diplomatic repercussions, particularly when they were so close to a deal just days ago.

On the other hand, it is unclear why the US has decided to withdraw from the prior deal, and whether this is some gamble on a quick Iranian concession or an effort to greatly prolong the negotiations.