The US deployed the USS Abraham Lincoln Carrier Strike Group to the Middle East on Monday as Washington strengthens its military presence in the region.

The Nimitz-class aircraft carrier enters the region "to promote regional security and stability," the US Central Command (CENTCOM) said through the US social media company X.

US President Donald Trump said Saturday that an American "armada" is heading toward the region, saying Washington is closely monitoring developments in Iran.

Previous assessments cited insufficient US military presence in the Middle East as limiting strike options in recent weeks, with officials noting "the theater was not ready" after assets shifted toward the Caribbean and Asia.

Military officials said back then that additional time is needed to prepare forces before any potential attack, according to US media reports.

Tens of thousands have rallied across Iranian cities over economic grievances and the rial's depreciation, prompting Trump to warn of a US "rescue" if protesters are killed, stating forces are "locked and loaded."

Trump has said he is weighing a "tough response," threatening action if mass executions proceed. However, he later softened his rhetoric, suggesting Tehran had stopped killing protesters after his warning.

Iranian officials warned any US attack would draw a "swift and comprehensive" response. (AA)