Two more detainees released from the Guantanamo Bay detention center in the first half of the year have rejoined militant groups, the White House announced Wednesday.

While President Obama slowly inched toward his goal of shutting down the U.S. detention center in Cuba holding foreign terrorism suspects, nine detainees released since 2009 later returned to fighting for militants groups, Reuters reported, citing a Office of Director of National Intelligence (ODNI) report.

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The administration has released 161 prisoners since Obama took office and 17 of them were released in the first half of 2009, according to the ODNI report. Though Obama’s predecessor, George W. Bush, released more than double the amount of detainees, 532, there were 113 of them that rejoined militant groups upon their release.

As a measure to block additional terror suspects from being discharged, Congress passed a bill Thursday prohibiting transfers from Guantanamo for the rest of Obama’s tenure as president or until the fiscal year 2017 National Defense Authorization Act passes — whichever comes first.

Democrats say the law, which passed in a 244-174 vote, is “probably unconstitutional and certainly immoral,” according to the Washington Examiner. Republican lawmakers, however, see it as a move toward strengthening national security.

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Missouri Rep. Vicky Hartzler thrust her support behind the law on the House floor, saying it “protects our troops, prevents further attacks on our families, and, just as importantly, ensures justice is served” for innocent Americans harmed by former GTMO detainees.

The bill falls on the heels of the single largest release of detainees under the Obama administration. In August, the Pentagon announced that fifteen GTMO prisoners, including 12 Yemeni nationals and three Afghans, were released and sent to the United Arab Emirates.

61 detainees remain at the detention center and 20 of them are cleared for release.