Washington (CNN) -- The first shipment of H1N1 vaccine set aside for U.S. troops deployed to Iraq and Afghanistan arrived late Tuesday, but it contains only half the amount requested.
The vaccine was at a base in Qatar and was to be distributed to bases in the region within 24 hours of its arrival there, according to Pentagon officials.
The U.S. Central Command, which includes Iraq and Afghanistan, asked for 300,000 doses to vaccinate U.S. troops in the war zones and other areas of the Middle East, but only about 150,000 have shown up, said Pentagon spokesman Geoff Morrell.
"We are doing everything within our power to make sure our guys downrange get this as soon as possible," he said.
It was unclear when the other 150,000 doses would arrive.
All the U.S. troops based in the Korean peninsula have been vaccinated against H1N1, but troops at the U.S. base at Guantanamo Bay, Cuba, are not scheduled to get vaccinations until the end of November, Morrell said at a Pentagon briefing.
He defended plans to vaccinate prisoners at the U.S. naval facility at Guantanamo Bay, Cuba, after criticism from members of Congress who said the detainees should not get the inoculations before U.S. citizens.
On Wednesday, three Republican U.S. senators introduced a resolution to postpone giving detainees the vaccine until Americans who are in priority groups -- such as children and pregnant women -- have been vaccinated.
"We should save the vaccine for those who need it most, and as of today, women, children and other at-risk individuals should fall squarely in line under that category. It should be made available to them before we hand it out to terrorists at Gitmo," said Sen. David Vitter, R-Louisiana, in a written statement. Vitter, along with Sen. Kay Bailey Hutchison, R-Texas, and Sen. John Cornyn, R-Texas, introduced the resolution.
"I can't speak to the protocols that will take place, stateside, in terms of how the general population is being handled, here. All I can tell you is that we have this very clear hierarchy of priorities for all of our bases across the world," Morrell said.
"We've got a five-category prioritization list. At the top of that hierarchy are U.S. forces. Number two on that list are deployed health care workers, both civilian and contractors. Number three are civilians," he said.
The Pentagon has said detainees at Guantanamo would be offered the vaccine after all U.S. active military and civilians at the Guantanamo base have been vaccinated.
As each U.S. base receives the vaccines, they are required to follow the priority list, starting with active duty troops.
"We haven't even taken care of the first lot or the second lot or the third lot before we'd even consider vaccinating anybody beyond that, including detainees," Morrell said. "There's no guarantee that everyone will get it. It depends on how many quantities are shipped to Guantanamo."
After the criticism about those being held at Guantanamo being vaccinated, the Pentagon on Tuesday clarified that detainees would not be getting the H1N1 vaccine before U.S. troops and civilians at the base.
Asked about the criticism, White House Press Secretary Robert Gibbs told reporters at a briefing Tuesday that no vaccines currently were being sent to Guantanamo.
What Gibbs left unsaid was that, ultimately, the detainees will be given the option to be vaccinated.