Bolivia has asked for the United Nations Security Council to meet on Thursday "on the escalation of rhetoric regarding Syria and these threats of unilateral military action," hours after US President Donald Trump warned of missile attacks.
"There's a consistency in these threats, so we are concerned because any unilateral action would be a violation of the principles and purposes of the (UN) charter," Bolivia's UN Ambassador Sacha Sergio Llorentty Soliz told reporters.
Trump warned Russia on Wednesday of imminent military action in Syria over a suspected deadly poison gas attack, declaring that missiles "will be coming" and lambasting Moscow for standing by Syrian President Bashar al-Assad. Dozens of people died and hundreds were injured in the attack, according to the World Health Organization (WHO).
The 15-member council failed on Tuesday to approve three draft resolutions on chemical weapons attacks in Syria. Russia vetoed a US text, while two Russian-drafted resolutions failed to get a minimum nine votes to pass.
"Whatever happens next has to abide by international law," Swedish UN Ambassador Olof Skoog told reporters on Wednesday, referring to US plans for military action.
Some diplomats said there were several arguments to justify bombing Syria over the suspected chemical weapons attack.
It could be argued a strike is being carried out in support UN Security Council resolutions, as was the case in 1998 when a US and British bombing campaign hit Iraqi weapons research and storage facilities to retaliate for the Iraqi government's refusal to cooperate fully with UN weapons inspectors.
Alternatively, a Syria strike could also be justified as action to stop the use or spread of weapons of mass destruction taken because the UN Security Council has been unable to act.
Any countries that carry out a strike on Syria over the chemical weapons attack could also defend their action under Article 51 of the UN Charter, which covers an individual or collective right to self-defense against armed attack.
"The use of chemical weapons, once allowed to spread, is a threat to everybody and if that takes hold and becomes a routine part of fighting, then we are all at risk," said Security Council diplomat, speaking on condition of anonymity.
In September 2014, the United States defended the start of its military action against Islamic State militants in Syria under Article 51. Washington argued it was attacking Islamic State group in Syria to eliminate a threat to Iraq, the United States and its allies.