Washington ( CNN ) -- U.S. troops based in South Korea have not been put on a heightened state of alert in the wake of that country 's announcement that North Korea was behind the sinking of one of its warships in March , the Pentagon said Thursday . At a Pentagon press briefing , U.S. Defense Secretary Robert Gates said the United States supports the findings of the investigation -- that the ship was sunk by a North Korean torpedo -- but he would not say what the United States is prepared to do , if anything , militarily . `` We are in close consultations with the South Koreans , '' Gates said . `` The attack was against one of their ships and , naturally , they will have the lead in laying out the path forward and we will be consulting with them very closely as we move ahead . '' Joint Chiefs of Staff Chairman Adm. Mike Mullen said the status of the 28,500 U.S. troops in South Korea has not changed because of the findings . `` They are on their normal state of readiness . They are engaged very routinely out there , '' Mullen said . `` We have a considerable number of forces stationed both on the land and sea and the forces are clearly aware of what 's going on , '' he said . Though Gates and Mullen would not speculate on what the next step would be for South Korea , the United States is bound by treaty to assist that nation if it goes to war . The U.S. Army is stretched thin in two wars in Iraq and Afghanistan , but Gates said there are other options in the case of armed conflict on the Korean peninsula . `` We have said for a long time that if there were a problem in Korea our main arms would be the Navy and the Air Force , and those are not stretched in the same way that the ground forces are , '' he said . Earlier Thursday , White House Press Secretary Robert Gibbs said the United States was `` in consultation with a host of different entities , including the [ U.N. ] Security Council ... and we 're working closely with the South Koreans . '' `` I think there 's a lot of things on the table '' in terms of possible responses , he added . Gibbs refused to comment on any specific response . Meanwhile , the State Department said the United States will send a clear signal to North Korea that the sinking of the warship was in violation of international norms and it must pay a price . `` Provocative actions will not be tolerated and ... there will be consequences for those , '' Assistant Secretary of State P.J . Crowley told reporters . `` At the same time , we will continue to try to see what can be done ... to continue to work towards a peaceful and stable Korean Peninsula and the broader region , '' he said . Crowley said the United States has a `` range of tools available '' to respond to the incident both unilaterally and collectively with other countries , including unilateral financial sanctions and other measures . However , he said , Washington will be guided by the actions the South Korean government wants to take . Asked whether the United States would consider putting North Korea back on the State Department 's list of state sponsors of terrorism , Crowley said it was unclear whether the ship incident would be considered an act of terrorism to meet the legal threshold for such a designation . The Bush administration took North Korea off the list in 2008 as part of negotiations on ending Pyongyang 's nuclear program . `` This is not something that anyone would do lightly , and there is an evidentiary standard here that has to be applied , '' Crowley said . `` Terrorism normally involves ... acts of violence against innocent civilians . You know , at one level this was a torpedo fired by one military vessel at another military vessel . '' Senior State Department officials said that although the department 's lawyers would make the final determination , the attack is not likely to be considered a terrorist attack because North and South Korea are technically at war . They pointed to a statement issued by the White House calling the attack an `` act of aggression '' and `` a violation of the Armistice Agreement . '' That 1953 agreement inaugurated an uneasy truce between the two Koreas , but no peace treaty has been signed to end the war . Additionally , the officials suggested that putting North Korea back on the terrorism list could be counterproductive because the United States was not the target of the attack .
the White House spokesman : U.S. has `` range of tools available '' to respond . U.S. in close consultation with South Korean , officials say . South Korea troops `` on their normal state of readiness , '' joint chiefs chairman says . Mike Mullen says U.S. must help U.S. in case of war .