Amid the ongoing diplomatic uncertainty set off by yesterday's attack on the British embassy in Iran, pundits, politicians and tweeps of all persuasions have been offering varying explanations of why the incident happened in the first place.

Most Western commentators seem convinced that the protesters who trashed the U.K. diplomatic compound could not have done so without the consent of Iranian authorities - a notion that today prompted the British government to expel Iran's own ambassadors from Great Britain.

What's behind the animosity between Iran and the U.K.? There was no shortage of opinions being expressed today on the subject, from a variety of different angles. Here is just some of what was making the rounds:

One word: Sanctions: Last week, Britain joined the U.S. and Canada in announcing newer, stricter economic sanctions against Iran. The U.K. cut all financial ties with Iran last Monday, the first time it has ever cut an entire country's banking sector off from British finance.Yesterday's protests have been portrayed as a reaction to those sanctions.

Sanctions and happenstance: While Britain was not alone in announcing sanctions, its embassy was unfortunately the most likely target for any protests, since it's primary partner, the United States, doesn't actually HAVE an embassy in Tehran. (America's own diplomatic mission was attacked and then evacuated in 1979 at the onset of Iran's Islamic revolution, and the U.S. has relied on the Swiss to conduct its relations with Tehran ever since.) With today's news that Britain will withdraw its own diplomats, that leaves Canada as the next biggest sanction-imposing nation with an embassy in Tehran. (Hmmm.)

Nuclear meddling: Vali Nasr, a professor of international politics at the Fletcher School of Law, doubted that sanctions alone were behind yesterday's events, tweeting this morning that "Attack on British embassy is more a reaction to chain of explosions and sabotage of nuclear facilities than response to sanctions." In the Daily Beast, Babak Dehghanpisheh pointed out that many of yesterday's protesters were carrying pictures of Majid Shahriari, a nuclear scientist assassinated last year, a murder that the regime in Iran has made a point of blaming on London.

What about the oil?: Twitter boasted a number of opinions on the embassy attacks, some of whom were quick to speculate on the role played by oil interests. Adding fuel to the fire? News that an oil embargo is on the way.

What about the bigger historical picture?: Some of the best analyses making the rounds today look past the sanctions, oil and nuclear meddling, and take a longer view - namely Britain's relationship with Iran since the imperial era. In these accounts, that Iranians would eventually express severe disdain for the U.K. pretty much appears to be a given, considering the checkered British history in their country. Outspoken and opinionated critic Robert Fisk takes this line of argument today in The Independent, while the BBC and Reuters present helpful historical summaries.