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Iranian lawmakers on Tuesday overwhelmingly approved a bill that labels all U.S. military forces as terrorist, state TV reported, a day after Washington ratcheted up pressure on Tehran by announcing that no country would any longer be exempt from U.S. sanctions if it continues to buy Iranian oil.

The bill is a step further from the one last week, when lawmakers approved labelling just U.S. troops in the Middle East as terrorist, in response to the U.S. terrorism designation for Iran's Revolutionary Guard earlier this month.

The Trump administration re-imposed sanctions on Iran, including on its energy sector, last November, after pulling America out of the landmark 2015 nuclear deal between Iran and world powers.

The U.S. designation against Iran's Revolutionary Guard — the first-ever for an entire division of another government — added another layer of sanctions to the powerful paramilitary force, making it a crime under U.S. jurisdiction to provide the guard with material support.

On Monday, President Donald Trump decided to do away with waivers as part of the administration's "maximum pressure" campaign on Iran that aims to eliminate all of its revenue from oil exports that the U.S. says funds destabilizing activity throughout the Mideast and beyond.

Hours before Trump's announcement, Iran reiterated its long-running threat to close the Strait of Hormuz if it's prevented from using the crucial waterway in the Persian Gulf through which about a third of all oil traded at sea passes. The U.S. Navy has in the past accused Iranian patrol boats of harassing American warships in the waterway.

Iran's Foreign Ministry promptly brushed off Trump's move to stop the oil waivers, saying the Islamic Republic "basically has not seen and does not see any worth and validity for the waivers."

But on Tuesday, 173 out of 215 lawmakers at the parliament session in Tehran voted for the new bill. Only four voted against while the rest abstained; the chamber has 290 seats.

The bill confirms Iran's earlier label of the U.S. Central Command, also known as CENTCOM, and all its forces as terrorist. Any military and non-military help, including logistics support, to CENTCOM that can be detrimental to the Revolutionary Guard will be considered a terrorist action, the semi-official ISNA news agency said.

The bill also demands the Iranian government take unspecified action against other governments that formally back the U.S. designation. Saudi Arabia, Bahrain and Israel have all supported the Trump administration's designation.

The lawmakers also requested Iran's intelligence agency provide a list of all CENTCOM commanders within three months so that Iran's judiciary can prosecute them in absentia as terrorists.

The bill requires final approval by Iran's constitutional watchdog to become law.

Other than underscoring Iran's defiance, it's unclear what impact the bill could actually have, either in the Persian Gulf or beyond. The Revolutionary Guard has forces and wields influence in Iraq, Syria, Lebanon and Yemen, and is in charge of Iranian missiles that have U.S. bases in their range.