Hours before additional U.S. sanctions on Iran come into effect, Secretary of State Mile Pompeo said on Sunday that the target of these sanctions is the Iranian regime, not the people.

Pompeo tweeted that the purpose of the sanctions is to compel Iran "to abandon its destructive activities." He added that the people of Iran have suffered enough and endured "their government's mismanagement, theft and brutality".

The second round of U.S. sanctions coming into effect mainly target Iran's oil exports and banking. President Donald Trump announced in May that the United States is withdrawing from the 2015 nuclear deal with Iran and will reimpose full sanctions.

In a second tweet, the secretary of state called attention to the 39th anniversary of the seizure of the U.S. embassy in Tehran and more than 50 American hostages.

The action was a clear violation of international law, condoned by Ayatollah Rouhollah Khomeini who was the leader of the Iranian revolution and the newly established Islamic state.

U.S.-Iranian diplomatic ties were severed and a tense cold war has prevailed since then.

Pompeo wrote in his tweet that the ordeal of the American hostages for 444 days compel the U.S. to be tough with Iran and force it to abandon its "outlaw activities".

In a remarkable development, the commander of Iran's IRGC admitted during a speech marking the seizure of the embassy today that top Iranian officials knew about the plan to attack and take over the U.S. mission in 1979.