WASHINGTON — US President Barack Obama, in his first extended comments on a partial Syria truce plan agreed upon with Russia that is set to go into effect Feb. 27, cautioned that it was likely to be messy and fragile, but he said the United States had little choice but to try to reduce the violence and save Syrian lives.

“None of us are under any illusions,” Obama said after meeting with his national security Cabinet at the State Department Feb. 25. “But history would judge us harshly if we did not do our part in at least trying to end this terrible conflict with diplomacy.”

In contrast with Russian President Vladimir Putin’s confident assertion in a Feb. 22 special television broadcast that the US-Russia partial truce accord could be a turning point in the Syrian crisis, the White House signaled far more doubt that the terms would not be violated and put most of the burden on Russia for seeing it through. The White House posture suggested it was approaching the Syria truce much as it had the 2013 agreement with Russia to remove Syria’s chemical weapons stockpile, which had been prompted by Obama’s threat to use force. Now, the White House seems to be calculating that Putin may be interested in a way to put Syria on a path toward stabilization after his military intervention last fall that has strengthened the diplomatic leverage of Syrian President Bashar al-Assad.

“Russia, and President Putin personally, have a lot of skin in the game,” White House spokesman Josh Earnest said Feb. 25. “And they’re on the hook for making sure that this understanding is successfully implemented.”