Diplomats from around the world are calling on the government of Syria's Bashar al-Assad to allow United Nations weapons inspectors to investigate the scene of where the Syrian opposition claims that chemical weapons were used to kill hundreds of civilians earlier this week, according to the Washington Post.

After months of arguing with al-Assad's government to be allowed in to the country the weapons inspectors had arrived in Damascus days before the alleged chemical attack, fueling speculation that the timing of the attack suggest that al-Assad's government wouldn't have used chemical weapons at that time.

An initial effort by the U.N. Security Council to have the attack on the suburbs of Damascus investigated as resisted by Russia, one of al-Assad's few remaining allies. After a phone call between U.S. Secretary of State John Kerry and Russia's Foreign Minister Sergei Lavrov the Russians changed their minds, according to the Washington Post.

"Immediately upon receipt of relevant information, the Russian side called on the government of Syria to cooperate with the U.N. chemical efforts," a statement from the Russian Foreign Ministry said. "The task now for the opposition is to provide secure access to the proposed site of the incident."

Leaders from some of the United States' key NATO allies - including France, the U.K. and Turkey - were quick to judge that al-Assad's forces used chemical weapons and that some sort of action is needed. In an interview with CNN President Barack Obama explained that the United States is going to tread lightly before intervening, according to Reuters.

"We are right now gathering information about this particular event, but I can say that unlike some of the evidence that we were trying to get earlier that led to a U.N. investigator going into Syria, what we've seen indicates that this is clearly a big event of grave concern," President Obama said. "The situation in Syria is very difficult and the notion that the U.S. can somehow solve what is a sectarian, complex problem inside of Syria is sometimes overstated..."

In a previous speech President Obama had referred to the use of chemical weapons as a "red line" that if Syria crossed it the U.S. would have to take action. Sen. John McCain, R-Ariz., believes that the president's lack of action to the most recent attack, as well as earlier suspected chemical attacks, shows that he is wavering on the idea of a red line, according to the BBC.

"Our friends and enemies alike, both in the Middle East and across the world, are questioning whether America has the will and the capacity to do what it says," McCain said in a statement. "This dangerous development impacts the national security interests of the United States and our closes allies, and if continue to sit by passively while Assad continues to use chemical weapons against his own people, we only provide encouragement to other brutal governments in their use of harsh measures against their own people. It is time for the United States to come to the assistance of the Syrian people."