Story highlights Al Qaeda's Ayman al-Zawahiri purportedly answers questions on range of subjects

He says "especially" American captives can be exchanged for al Qaeda captives

Egypt's Muslim Brotherhood has "the right to use force," al-Zawahiri adds

He predicts "the mujahedeen" and ardent followers will prevail in Yemen

In the second part of a long-ranging interview, al Qaeda's leader urged Muslims to capture Westerners as pawns that might be used to free prisoners aligned with his movement.

Asked what he'd tell "Muslims and the mujahedeen" -- a term used for some Islamist militants -- to do to "fulfill their duty" toward their allies in custody, Ayman al-Zawahiri said, "I advise them to capture Westerners -- and especially the Americans, as much as they can -- to exchange them for our captives."

This was one of many comments on a wide array of topics that al-Zawahiri touched on in a question-and-answer session with al Qaeda's media arm, audio of which was published on the radical Islamist website Hanein. CNN cannot independently verify the authenticity of the recording, though the voice appears very similar to previous messages from al-Zawahiri.

In the first part of the interview , which was posted online a week ago, al-Zawahiri insisted that al Qaeda is holding strong and, in fact, "expanding" 13 years after the United States launched its "war on terror" following the September 11, 2001, attacks.

"The upper hand is for the one who does not withdraw from his land," he said. "Who has withdrawn from Iraq, and who has not? Who has withdrawn from Afghanistan and who has not?"

The second part of the interview was apparently published last Saturday. CNN learned about this part of the exchange via the SITE Intelligence Group , which monitors terror-related websites.

In it, al-Zawahiri expresses solidarity with the Muslim Brotherhood in its struggle with Egypt's military-led government. Voters elected that Islamist group's candidate, Mohammed Morsy, as president -- a decision the al Qaeda leader said "the West, led by America," did not respect.

Since then, the Cairo government has banned the Brotherhood and detained many of its leaders, including the now-ousted Morsy. Al-Zawahiri said the Islamist group has "all the right to use force against the injustice they are facing."

"The secularists and the army attacked them with Gulf money, American planning, Israeli incitement and crusader plotting," he added.

Al-Zawahiri also discussed Yemen, where the United States and its allies have been working with the Sana'a-based government to go after members of al Qaeda in the Arabian Peninsula.

A combination of ground assaults and airstrikes -- including by suspected U.S. drones -- April 19-21 killed more than 60 suspected al Qaeda militants , Yemeni officials have said.

No reference was made to that operation in al-Zawahiri's interview posted to Hanein. In fact, it's not known exactly when he may have conducted the interview.

Some in Yemen affiliated with "the Islamist movements" have "conspired" with that Arab nation's government "by participating or remaining silent to the American presence and its repetitive aggression against the Yemeni people," al-Zawahiri said. It's a position they'll ultimate regret, he surmised.

The al Qaeda leader predicted, "It is the mujahedeen and the people of ardency from among the Yemeni people and its scholars, its true-born and its chiefs and their sheikhs (who will prevail)."