The United States said the Syrian government is defying the international community's support of the country's peace talks after the reported detention of people related to opposition delegates taking part in the negotiations.
State Department spokeswoman Jen Psaki said in a statement late Wednesday the tactics are "not new behavior," and called on President Bashar al-Assad's government to immediately release those "unfairly arrested."
She highlighted the case of Mahmoud Sabra, the brother of an opposition delegate who the Syrian National Coalition said last week was arrested at a checkpoint and thought to be held by security forces in southern Damascus.
So far, two rounds of peace talks with U.N.-Arab League envoy Lakhdar Brahimi have produced little progress.
U.S. Secretary of State John Kerry responded to critics Wednesday, saying it is "asinine" to already characterize the process as a failure.
He cited the Vietnam War peace talks, which took more than four years, and the three years it took to resolve the conflict in Bosnia.
Psaki gave a similar message during a press briefing Wednesday, saying peace negotiations can take a very long time.
"Obviously, there are many multiple paths we're working on through the U.N., through engagement with countries in the region, engagement with the Russians, continuing to press the Syrian regime publicly to take more steps. So we're not resting on one step, and we'll see where it goes moving forward. But the most important piece here is that this has also kind of reinvigorated a unity among the international community about the path that is necessary moving forward, which is the implementation of the Geneva communique and the creation of a transitional governing body," said Psaki.
The Syrian conflict has stretched on for nearly three years, with the fighting killing well over 100,000 people and forcing more than 9 million from their homes.
Kerry said in an interview Wednesday with MSNBC that Assad is carrying out "wholesale killing" of his own people, and called the government's actions "unconscionable," "disgraceful" and "horrendous."
He said President Barack Obama is constantly assessing further options without taking any off the table, and that his administration is putting every energy into the situation in Syria.
Kerry said he is continuing to talk to allies, and that Syria will be a part of discussions next week as foreign ministers gather in Paris and Rome for conferences focusing on Lebanon and Libya.
He also said Russia is "increasing its assistance to Assad," which he said is not helping efforts to get the Syrian president to negotiate with the opposition in good faith.