Sen. John McCain, R-Ariz., has threatened to subpoena 10 U.S. sailors if the Obama administration doesn't soon release more details about the sailors' January detention by Iran.

McCain, who has been highly critical of the nuclear deal with Iran, said he doesn't want to subpoena the sailors, but said he would if the administration doesn't release the findings of an investigation into the incident by March 1.

The Republican told reporters it's an option "I do not want to exercise" as he was returning to the U.S. from an international security conference in Germany. McCain chairs the Senate Armed Services Committee.

The Obama administration has said the release of the sailors after they were held just one day by the Islamic Revolutionary Guard Corps is an example of its effective diplomacy. Iran freed them after negotiations between Secretary of State John Kerry and Iranian Foreign Minister Javad Zarif, just days before the Iran nuclear deal was implemented and its international sanctions were lifted.

But Republicans, including McCain, say they want a better explanation of how two patrol boats the sailors strayed into Iranian waters on Jan. 12. Officials have said it was because of a navigational problem.

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In some videos of the detainees broadcast by Iranian media, the sailors were shown kneeling as Iranian personnel aimed weapons at them. After their release, Kerry said there was evidence the sailors were "well taken care of," a statement McCain and some of the Republican presidential candidates blasted.