US President Barrack Obama said that the US aid may not reverse what the interim government is doing, adding that Americans have to be very careful about being seen as aiding and abetting actions that the US thinks run contrary to its values and ideals. In an interview broadcasted Friday on CNN\'s \"New Day,\" Obama said the administration is currently \"doing a full evaluation of the U.S.-Egyptian relationship,\" and that there is \"no doubt that we can\'t return to business as usual, given what\'s happened.\" The US congress is pushing to cut off over $1.2 billion in US aid to the military-backed government in Egypt. So far, the Pentagon has canceled upcoming military exercises and delayed the delivery of fighter jets, and is reviewing all other aspects of assistance, including military and economic help. \"There was a space right after Morsi was removed in which we did a lot of heavy lifting and a lot of diplomatic work to try to encourage the military to move in a path of reconciliation,\" the president added. But \"they did not take that opportunity.\" Turing to the situation in Syria, Obama said that the US remains \"one indispensable nation\" in the volatile Middle East and elsewhere. \"We have to think through strategically what\'s going to be in our long term national interests,\" he added. Asked about claims by anti-regime activists in Syria that Bashar al-Assad\'s government used chemical weapons in an attack that was said to have killed more than 1,300 people, Obama responded that officials are \"right now gathering information\" and that \"what we\'ve seen indicates that this is clearly a big event of grave concern.\" \"It is very troublesome,\" the president stressed. Obama said US officials are pushing \"to prompt better action\" from the United Nations, and are calling on the Syrian government to allow an investigation of the site of the alleged attack outside Damascus. \"We don\'t expect cooperation (from the Syrian government), given their past history,\" Obama conceded. He quickly followed up with a warning, however, that \"core national interests\" of the US are now involved in Syria\'s civil war, \"both in terms of us making sure that weapons of mass destruction are not proliferating, as well as needing to protect our allies, our bases in the region.\" Obama warned against getting \"mired in very difficult situations ... (and) being drawn into very expensive, difficult, costly interventions that actually breed more resentment in the region.\" Administration officials confirmed in June that chemical agents were used in April, resulting in an uptick of military aid to rebels that did little to assuage White House critics. \"If the US goes in and attacks another country without a UN mandate and without clear evidence that can be presented, then there are questions in terms of whether international law supports it,\" Obama explained. The costs of military action \"have to take those into account as we try to work within an international framework to do everything we can to see Assad ousted,\" Obama concluded.