On Monday, the United States re-imposed a second round of sanctions on Iran, targeting the country's energy, shipping, banking and shipbuilding sectors. In addition, having initially talked of cutting Iranian oil shipments to zero, Washington gave waivers to eight customers, raising the prospect of more Iranian oil in the market than expected.
A dozen Iranian tankers have turned off their transponders as a tactic to evade sanctions, US Special Representative for Iran Brian Hook said in a press briefing.
The move by the Donald Trump administration is considered as an endorsement by Washington of India's major role in the development of the port on the Gulf of Oman, which is of huge strategic importance for the reconstruction of war-torn Afghanistan.
On Tuesday, the State Department clarified that Chabahar and an Afghanistan specific railway project (under INSTC) would be kept out of the sanctions for the objective of "development" of Afghanistan.
The U.S. sanctions on Tehran come as the Trump administration withdrew from the 2015 nuclear deal with Iran in May, saying it had not stopped Iran from developing its ballistic missile program and intervening in neighboring countries.
President Donald Trump's "South Asia strategy underscores our ongoing support of Afghanistan's economic growth and development as well as our close partnership with India", a State Department spokesman said on November 6. "We seek to build on our close relationships with both the countries as we execute a policy of maximum pressure to change the Iranian regime's destabilising policies in the region and beyond".
The sanctions, however, threatened India's ability to obtain financing for the development of Chabahar, which could potentially open the way for millions of dollars of trade for land-locked Afghanistan and end its dependence on Pakistan's port of Karachi. "These activities are vital for the ongoing support of Afghanistan's growth and humanitarian relief", said the US State Department Spokesperson.
New Delhi has poured $2 billion into development in Afghanistan since the 2001 USA -led overthrow of the Taliban government.
"This exception relates to reconstruction assistance and economic development for Afghanistan".
The sanctions reimposed on Iran's oil exports - its main revenue source - and financial sector were triggered by US President Donald Trump's May 8 decision to abandon the 2015 global deal created to block Tehran's development of nuclear weapons.