Secretary of State Condoleezza Rice and British Foreign Secretary David Miliband made an unannounced visit to Afghanistan on Thursday. It comes a day later after their visit in London.

They carried a message of support as the U.S. is continuing to recruit more NATO troops.

The two are expected to meet Afghan President Hamid Karzai and other military officials.

Rice said: "The Afghan government has responsibilities, too. This is a two-way street, and I think everybody has to step back and concern ourselves with the Taliban," the Associated Press reports.

Miliband said: "We've got responsibilities that we're determined to live up to and obligations that we're determined to live up to and ditto for the Afghan authorities. That's something we want to follow through and at the heart of both our strategies is the belief this has to be done with the Afghan government and in fact led by the Afghan government, with our support."

Defense Secretary Robert Gates said that the future of NATO depends on whether members will send troops to Afghanistan. He added that without new troops those who are engaged in the battle will lose their will, and NATO will become a “two-tier alliance.”

He said from Washington: "I think that it puts a cloud over the future of the alliance if this is to endure and perhaps even get worse."

Most of the troops that carry the fighting in Afghanistan come from the U.S., the U.K. Canada, the Netherlands, Denmark and Romania while the other members like Spain, France, Germany, Turkey and Italy has only sent a little number of combat forces.

Gates said that he sent letters to the other countries for the extra troops and he reluctantly agreed to send the 3,000 U.S marines.

Right now there are almost 43,000 troops in the NATO-led coalition, 16,000 are U.S troops. Other 13,000 U.S. troops are there to train Afghan forces and to hunt al-Qaeda terrorists.

On Thursday Gates is scheduled to meet the NATO defense ministers in Vilnius, Lithuania.

He said on Wednesday: "I worry a great deal about the alliance evolving into a two-tiered alliance, in which you have some allies willing to fight and die to protect peoples' security, and others who are not. And I think that it puts a cloud over the future of the alliance if this is to endure, or perhaps even get worse." BBC News reports.