The United States on Sunday imposed sanctions over Iran's ballistic missile testing even as President Barack Obama hailed the release of five Americans from Tehran's custody and the implementation of a nuclear deal he hopes will stand among his lasting foreign policy achievements.

With a set of international nuclear sanctions on Iran being lifted, India will be able to resume its unrestricted import of oil from the Persian Gulf nation.

State-run Indian Oil Corp (IOC) in New Delhi told IANS that the possibility of freely importing oil from Iran, to be paid for now in US dollars, comes at a time when global prices are expected to plunge further with Iranian oil adding to the supply glut.

Iran is expected to increase its export of 1.1 million barrels of oil per day by 500,000 soon, followed by a further 500,000 bpd thereafter.

The lifting of sanctions came after US Secretary of State John Kerry issued a statement confirming the International Atomic Energy Agency has verified that Iran "has fully implemented its required commitments".

Meanwhile, on Sunday itself, the United States on Sunday imposed a different set of sanctions over Iran's ballistic missile testing even as President Barack Obama hailed the release of five Americans from Tehran's custody and the implementation of a nuclear deal he hopes will stand among his lasting foreign policy achievements.

Obama pledged to counter vigorously Iran's "destabilizing behavior" across the Mideast even while the US engages with the Islamic Republic. After the Americans had been freed, Obama announced economic sanctions against 11 individuals and entities as a result of a ballistic missile launch in October.

"We're not going to waver in the defense of our security or that of our allies and partners," Obama said.

Meanwhile, on Sunday itself, with a different set of international nuclear sanctions on Iran being lifted, India will be able to resume its unrestricted import of oil from the Persian Gulf nation.

On the other hand, with the new sanctions announcement, Obama also sought to counter criticism from Republican lawmakers and presidential candidates that his actions had appeased a nation that has aided the spread of Islamic extremism.

"It reflects a pattern we've seen in the Obama administration over and over again of negotiating with terrorists and making deals and trades that endanger US safety and security," Texas Sen. Ted Cruz, a leading Republican presidential contender, said on Fox News Sunday.

"Our enemies now know that if you can capture an American, you can get something meaningful in exchange for it," another Republican candidate, Florida Sen. Marco Rubio, said on NBC's Meet the Press.

But Obama said he decided "that a strong confident America could advance our national security by engaging directly with the Iranian government."

Democratic lawmakers who supported the agreement applauded the sanctions announced Sunday. Five Democratic senators said in a joint letter to Obama that failure to impose the restrictions could encourage Tehran to violate international obligations with impunity.

The Obama administration worked for nearly 14 months behind the scenes to negotiate the prisoner trade. Iran also agreed to work to locate American Robert Levinson, who vanished during a trip to Iran in 2007.

In a reciprocal move, Obama said that six Iranian-Americans and one Iranian serving sentences or awaiting trial in the U.S. were being granted clemency. He emphasized that they were not charged with terrorism or any violent offenses.

"They're civilians, and their release is a one-time gesture to Iran given the unique opportunity offered by this moment and the larger circumstances at play," Obama said.

Obama said the US and Iran had also resolved a longstanding dispute over money Iran used to buy military equipment from the U.S. before the two countries broke ties. Iran will get more than $400 million, plus $1.3 billion in interest.

The White House said its lawyers assessed that the U.S. could have faced a "significantly higher judgment" if the case continued.

"There was no benefit to the US is dragging this out," Obama said.

Obama used his Sunday morning statement from the White House to speak directly to the Iranian people: "We have a rare chance to pursue a new path — a different, better future that delivers progress for both our peoples and the wider world."

Obama said Iran has a vibrant culture that has so much to contribute to the world in commerce, science and the arts, but "your government's threats and actions to destabilize your region have isolated Iran from much of the world."

The Obama administration said it was prepared to test whether additional cooperation with Iran was possible, most notably in resolving the civil war in Syria.

White House officials said during a briefing held after the president's address that Iran could play a significant role in resolving the Syrian civil war, but profound differences exist. They said Iran needs to understand the fighting won't be resolved as long as Syrian President Bashar Assad remains in power.

The officials said they know Iran is not going to dramatically change its actions in the next year or two.

"If Iran does act in a more constructive fashion, it would be a positive development in resolving difficult issues," the White House officials said. "If they don't, we will continue to enforce our sanctions and continue to have very strong differences."

With inputs from agencies