Islamabad , Pakistan ( CNN ) -- The U.S. military says only one supply route to Afghanistan has been closed by the Pakistani government after fighting that led to the deaths of three Pakistani soldiers , and a military spokesman said Thursday that United States is hopeful the situation is only temporary . Pakistan banned NATO supply convoys from entering Afghanistan after the deaths of the three soldiers , whom the government says were killed in Pakistani territory during fighting between NATO troops and militants , according to a military official from the NATO-led command in Afghanistan . Lt. Col. John Dorrian , an ISAF spokesman , said the Torkham Gate in the Khyber Agency has been closed since about midday on Thursday . Chaman Gate , the other border crossing between Pakistan and Afghanistan , remains open . `` We do n't think it 's a very serious problem , '' Dorrian said . `` it 's a throroughfare we use a lot so it is significant . But we can work around it . '' `` We do expect these matters to be resolved . '' The U.S. Embassy in Islamabad is talking with Pakistan to resolve the situation . Supply convoys are all-important for the Afghan war effort , and officials from NATO 's International Security Assistance Force ( ISAF ) were trying to persuade Pakistan to lift the ban . Coalition forces rely heavily on convoys from Pakistan to bring in supplies and gear . Torkham Gate is one of the main ports of entry for materiel coming into the war zone . But he emphasized it 's not the only way of getting supplies in , he said . Khyber Agency is one of the seven districts in Pakistan 's tribal region . About half the cargo that flows into Afghanistan comes in via one of the two gates from Pakistan , the Defense Department says . Another 30 percent uses two major routes through Kazakhstan and Uzbekistan , one via Russia and the other via the Caucasus . The remaining 20 percent -- mostly sensitive items like weapons , ammunition and other critical equipment -- comes in by air . ISAF said in a statement Thursday that its forces saw what they thought were insurgents trying to fire mortars at a coalition base in the Dand Patan District of Afghanistan 's Paktiya province , near the Pakistani border . An air weapons team targeted the suspected insurgents ' firing position , located inside Afghanistan along the border area , and the aircraft entered Pakistani airspace briefly `` as they engaged this initial target , '' the ISAF statement said . After this strike , the `` aircraft received what the crews assessed as effective small arms fire from individuals just across the border in Pakistan '' and the ISAF aircraft , operating in self-defense , entered into Pakistani airspace and killed `` several armed individuals . '' Later , Pakistani military officials told ISAF that coalition aircraft struck its border forces . `` ISAF and Pakistani forces are reviewing the operational reporting to verify the exact location of the two engagements and the facts in this case , and we will work together to fully investigate this incident . `` Both sides have in mind that it is the insurgents , operating on the border between Pakistan and Afghanistan and violating the territorial sovereignty of both countries , that we are focused on fighting , '' the ISAF statement said . ISAF issued `` sincere condolences to the Pakistani military and the families of those who were killed or injured . '' The Pakistani government said two helicopters from Afghanistan appeared to have crossed the border into Pakistan in the Mandata Kandaho , Ali Mangola area of the upper Kurram Agency and engaged an outpost of Frontier Corps through cannon fire . The post , manned by six soldiers , is located 200 meters inside Pakistan , and troops fired their rifles to indicate that the helicopters were crossing into Pakistani territory . Instead of heeding the warning , the choppers fired two missiles and destroyed the post , killing the three soldiers and injuring three others . `` This is the third incident of its kind during past one week . In the wake of the last incident on 27 September , contact was made at the highest military level and the incident was regretted by the USA , '' the government said . NATO helicopters crossed into Pakistani airspace from Afghanistan in pursuit of insurgents over the weekend , killing 49 people , a spokesman told CNN Monday . Crossing the border did not violate the International Security Assistance Force rules of engagement , Maj. Michael Johnson said . Pakistan is very sensitive about U.S.-led military operations on its territory and issued a strong protest Monday . Pakistan called the incursions `` a clear violation and breach '' of U.N. rules for foreign forces in Afghanistan . The United Nations `` mandate terminates/finishes at the Afghanistan border . There are no agreed hot pursuit rules , '' Pakistan 's Foreign Ministry said in a statement . A commander of international forces in the western part of Afghanistan said Thursday that Pakistan 's recent ban on use of supply routes is `` not a problem '' for troops in his area of the country . Italian Gen. Claudio Berto , talking to reporters in the Pentagon via satellite from Afghanistan , said , `` In my point of view , it 's not a problem , we are really far away from Pakistan , and if you mean the goods for the soldier , they 're coming through other borders , for example Turkmenistan . And we have no problem with this issue . ''
NEW : About half of U.S. cargo comes into Afghanistan via Pakistan , Pentagon says . Comment: Spokesman : `` We do n't think it 's a very serious problem '' Pakistan says 3 of its soldiers were killed during NATO attack on insurgents .