Tehran ? Iran’s supreme leader pledged Friday to aid any nation or group that challenges Israel and said any military strikes over the Islamic Republic’s nuclear program would damage U.S. interests in the Middle East “10 times over.”

The nationally broadcast comments by Ayatollah Ali Khamenei staked out a hard line in apparent replies to suggestions that military strikes are an increasing possibility if sanctions fail to rein in the Islamic Republic’s nuclear program.

It also may signal that Tehran’s proxy forces — led by Lebanon’s Islamic militant group Hezbollah — could be given the green light to revive attacks on Israel as the showdown between the archfoes intensifies.

The West and its allies fear Iran could use its uranium enrichment labs — which make nuclear fuel — to eventually produce weapons-grade material. Iran insists it only seeks reactors for energy and medical research.

Israel has so far publicly backed the efforts by the U.S. and European Union for tougher sanctions that target Iran’s crucial oil exports. But Israeli leaders have urged even harsher measures and warn that military action remains a clear option despite Western appeals to allow time for the economic pressures and isolation to bear down on Iran.

Although Israel has raised the strongest hints over a military campaign, Khamenei reserved some of his strongest comments for Israel’s key U.S. ally.

“A war itself will damage the U.S. 10 times over” in the region, said Khamenei.

Khamenei claimed Iran, however, could only emerge stronger. “Iran will not withdraw. Then what happens?” asked Khamenei. “In conclusion, the West’s hegemony and threats will be discredited” in the Middle East. “The hegemony of Iran will be promoted. In fact, this will be in our service.”

On Thursday, Israel’s defense minister, Ehud Barak, suggested the world is increasingly ready to consider a military strike if sanctions fail. The head of the country’s strategic affairs ministry, Vice Premier Moshe Yaalon, also suggested Iran’s main military installations are still vulnerable to airstrikes — even as Iran starts up a new uranium enrichment facility deep in a mountainside bunker south of Tehran.

Yaalon’s comments appear to reinforce earlier suggestions by other Israel officials that the window for a possible attack is closing and Israel would need to strike by summer to inflict significant setbacks on Iran’s nuclear facilities. The officials spoke on condition of anonymity under standing guidelines.

At Ramstein Air Base in Germany, U.S. Defense Secretary Leon Panetta said sanctions remain the best approach to pressure Iran. But he told U.S. airmen Friday that Washington keeps “all options on the table and would be prepared to respond if we have to.”

Khamenei answered by repeating Iran’s declarations that it will never roll back its nuclear program, which he had earlier said was now part of the country’s “identity” and a cornerstone of its technological endeavors. On Friday, Iran said it successfully sent a small satellite into orbit in the third such launch in recent years, state media reported.

“From now on, in any place, if any nation or any group confronts the Zionist regime, we will endorse and we will help. We have no fear expressing this,” said Khamenei, using the phrase widely used by Iran’s leader to describe Israel.