Iranian officials struck a defiant posture on Thursday in response to a proposed oil embargo by the European Union, calling the intensified efforts to halt Iran’s nuclear program, including new sanctions by United States, tantamount to “an economic war.”

The strong words were the latest in a series of escalating military and diplomatic responses by Iran in recent weeks amid growing pressure from Western powers. On Tuesday, Iran warned the United States that it would take action if an American aircraft carrier that left the Persian Gulf through the Strait of Hormuz were to return. The United States has said that the threats would not cause it to alter military deployments.

Britain added its voice to the chorus on Thursday, with Defense Secretary Philip Hammond cautioning that any attempt by Iran to close the strait would be “illegal and unsuccessful.” His comments, delivered during his first visit to the Pentagon since he became the top defense minister last fall, appeared to indicate strong resolve by the West to keep the strategically important strait open for trade. “It is in all our interests that the arteries of global trade are kept free, opening and running,” he said, according to news reports.

The official news agency IRNA quoted one senior member of the Iranian Parliament as saying that pressure from “bullying nations” made the country “more resilient.” Press TV, an official Iranian news site, headlined its report with a warning against “saber rattling” by Britain.