WASHINGTON — As the Syrian regime and opposition trade accusations over the use of chemical weapons, the drumbeat in Washington for the United States to get more directly involved in the two-year old conflict is growing louder.

Republican Senators Lindsey Graham and John McCain released a statement today, calling for President Obama to act against Syrian President Bashir al-Assad.

State Department spokeswoman Victoria Nuland said the U.S. was looking into claims that the Assad regime had used a chemical weapon in a recent attack in the opposition stronghold of Aleppo. She would not confirm whether the administration believes Syria’s chemical stockpile is secure, citing intelligence reasons, but said there continues to be an increasing concern that Assad will cross that line.