The Guardian | Simon Tisdall: Frustration in Washington at its failing foreign policies could be a factor in growing pressure

John Bolton�s sudden, unexplained threat to use �unrelenting force� against Tehran has raised US-Iran tensions to a new high. But its impact is not confined to these two countries. Like a lethal poison, their mutual enmity is seeping through the veins of an already unstable region that has experienced dangerously high levels of volatility in recent days.

No clear reason was given by Donald Trump�s national security adviser for his decision to advertise the pre-arranged deployment of military reinforcements to the Middle East. But Bolton singled out Iran, and specifically Iran�s non-state allies and proxy forces, as causes for concern. These groups are deeply involved in several conflict zones including Syria, Iraq, Yemen and Gaza, where fighting with Israeli forces re-erupted last week.

�The US is not seeking war with the Iranian regime, but we are fully prepared to respond to any attack whether by proxy, the Islamic Revolutionary Guard Corps [IRGC] or regular Iranian forces,� Bolton said.

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