Warning of "unintended consequences" if Pakistan did not act against the "non-state actors" who used its territory to stage attacks in Mumbai, the US on Wednesday said it was "working hard" to verify what Islamabad [Images] was actually doing against such elements.

'I think we have to be concerned because it's obviously a time of great outrage in India. And what I emphasised was that this was a threat to both Pakistan and India these terrorists," Secretary of State Condoleezza Rice [Images] said in an interview to the National Public Radio.

Pakistan, she stressed, needed to act since its territory had been used by "these non-state actors to make those (Mumbai) attacks."

"Also, Americans were killed, which gave the United States a special responsibility," Rice said.

Amid reports of arrest in Pakistan of Zakiur Rehman Lakhvi and Zarar Shah, the two top commanders of LeT which is blamed for the Mumbai strikes, she said she was "pleased" to see that some "important steps" are being taken in Pakistan.

"We are working hard to try and clarify and verify what is actually happening there, but there seem to be some positive steps being taken. The people who did this also wanted to abort what has been a positive direction in Pakistani-Indian relations," Rice said.

Noting that India and Pakistan were on the brink of war after the 2001 attack on Indian parliament, she said the ties between the two countries are "very different now."

"The Pakistani Government is a civilian government, a legitimate civilian government that has been reaching out to India, and vice versa. The Pakistani Foreign Minister was actually in India at the time that this took place. And so we have a lot to work with, and I think we're making some progress," Rice said.