President Obama may have lost Great Britain as an official option in a discussed military strike on Syria, but he has other options, like Germany, for example. While Germany can do little in the way of waging war, thanks to provisions installed after World War II, it can at least provide monetary help.
Perhaps that’s why President Obama called Chancellor Merkel. According to the White House:
The President and Chancellor Merkel spoke today to discuss their grave concern about the indiscriminate use of chemical weapons on August 21 in Syria. The two leaders agreed that the use of chemical weapons is a serious violation of international norms and pledged to continue to consult closely on potential responses by the international community.